Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Feb. 20, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q4
Trading Symbol	DCP
Entity Registrant Name	DCP MIDSTREAM, LP
Entity Central Index Key	0001338065
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		143,317,328
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 3,577,813,000

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 1	$ 156
Accounts receivable:
Trade, net of allowance for doubtful accounts of $3 and $8 million, respectively	860	773
Affiliates	166	191
Other	7	17
Inventories	79	68
Unrealized gains on derivative instruments	108	30
Collateral cash deposits	34	75
Other	16	12
Total current assets	1,271	1,322
Property, plant and equipment, net	9,135	8,983
Goodwill	231	231
Intangible assets, net	97	106
Investments in unconsolidated affiliates	3,340	3,050
Unrealized gains on derivative instruments	8	3
Other long-term assets	184	183
Total assets	14,266	13,878
Accounts payable:
Trade	807	989
Affiliates	96	68
Other	23	19
Current debt	525	0
Unrealized losses on derivative instruments	91	76
Accrued interest	71	71
Accrued taxes	64	58
Accrued wages and benefits	64	65
Capital spending accrual	63	39
Other	100	103
Total current liabilities	1,904	1,488
Long-term debt	4,782	4,707
Unrealized losses on derivative instruments	8	15
Deferred income taxes	32	29
Other long-term liabilities	243	201
Total liabilities	6,969	6,440
Commitments and contingent liabilities (see note 14)
Equity:
Limited partners (143,317,328 and 143,309,828 common units authorized, issued and outstanding, respectively)	6,418	6,772
General partner	107	154
Accumulated other comprehensive loss	(8)	(9)
Total partners’ equity	7,268	7,408
Noncontrolling interests	29	30
Total equity	7,297	7,438
Total liabilities and equity	14,266	13,878
Series A Preferred Limited Partners [Member]
Equity:
Preferred Units, Preferred Partners' Capital Accounts	489	491
Total equity	489	491
Series B Preferred Limited Partners [Member]
Equity:
Preferred Units, Preferred Partners' Capital Accounts	156	0
Total equity	156	0
Series C Preferred Limited Partners [Member]
Equity:
Preferred Units, Preferred Partners' Capital Accounts	106	0
Total equity	$ 106	$ 0

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Allowance for Doubtful Accounts Receivable, Current	$ 3	$ 8
Common unitholders, units issued (in shares)	143,317,328	143,309,828
Common unitholders, units outstanding (in shares)	143,317,328	143,309,828
Series A Preferred Limited Partners [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Preferred Units, Issued	500,000	500,000
Preferred Units, Outstanding	500,000	500,000
Series B Preferred Limited Partners [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Preferred Units, Issued	6,450,000	0
Preferred Units, Outstanding	6,450,000	0
Series C Preferred Limited Partners [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Preferred Units, Issued	4,400,000	0
Preferred Units, Outstanding	4,400,000	0

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating revenues:
Sales of natural gas, NGLs and condensate	$ 9,374	$ 7,850	$ 6,269
Transportation, processing and other	489	652	647
Trading and marketing losses, net	(41)	(40)	(23)
Total operating revenues	9,822	8,462	6,893
Operating costs and expenses:
Purchases and related costs	8,019	6,885	5,461
Operating and maintenance expense	760	661	670
Depreciation and amortization expense	388	379	378
General and administrative expense	276	290	292
Asset impairments	145	48	0
Other expense (income), net	11	11	(65)
Gain on sale of assets, net	0	34	35
Restructuring costs	0	0	13
Total operating costs and expenses	9,599	8,240	6,714
Operating income	223	222	179
Loss from financing activities	(19)	0	0
Earnings from unconsolidated affiliates	370	303	282
Interest expense, net	(269)	(289)	(321)
Income before income taxes	305	236	140
Income tax expense	(3)	(2)	(46)
Net income	302	234	94
Net income attributable to noncontrolling interests	(4)	(5)	(6)
Net income attributable to partners	298	229	88
Net loss attributable to predecessor operations	0	0	224
Series A preferred limited partners' interest in net income	(37)	(4)	0
Series B preferred limited partners' interest in net income	(8)	0	0
Series C preferred limited partners' interest in net income	(2)	0	0
General partner’s interest in net income	(164)	(164)	(124)
Net income allocable to limited partners	$ 87	$ 61	$ 188
Net income per limited partner unit — basic and diluted	$ 0.61	$ 0.43	$ 1.64
Weighted Average Limited Partnership Units Outstanding, Basic	143.3	143.3	114.7
Affiliated Entity
Operating revenues:
Sales of natural gas, NGLs and condensate	$ 1,610	$ 1,274	$ 952
Operating costs and expenses:
Purchases and related costs	896	577	483
Third Party
Operating revenues:
Sales of natural gas, NGLs and condensate	7,764	6,576	5,317
Operating costs and expenses:
Purchases and related costs	$ 7,123	$ 6,308	$ 4,978

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 95	$ 82	$ 62	$ 63	$ 64	$ (20)	$ 89	$ 101	$ 302	$ 234	$ 94
Other comprehensive income:
Reclassification of cash flow hedge losses into earnings									1	1	0
Total other comprehensive income									1	1	0
Total comprehensive income									303	235	94
Total comprehensive income attributable to noncontrolling interests									(4)	(5)	(6)
Total comprehensive income attributable to partners									$ 299	$ 230	$ 88

Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Series A Preferred Limited Partners [Member]	Series B Preferred Limited Partners [Member]	Series C Preferred Limited Partners [Member]	General Partner	Limited Partners	Accumulated Other Comprehensive (Loss) Income	Noncontrolling Interests
Beginning balance (Predecessor) at Dec. 31, 2015	$ 4,287
Beginning balance at Dec. 31, 2015	7,092				$ 18	$ 2,762	$ (8)	$ 33
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income \| Predecessor	(224)
Net income	94				124	188		6
Other comprehensive income	0
Net change in parent advances \| Predecessor	(157)
Net change in parent advances	(157)
Proceeds from Issuance of Preferred Limited Partners Units	0
Distributions to unitholders	(483)				(124)	(359)
Distributions to noncontrolling interests	(7)							(7)
Ending balance (Predecessor) at Dec. 31, 2016	4,220
Ending balance at Dec. 31, 2016	6,853	$ 0			18	2,591	(8)	32
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income \| Predecessor	0
Net income	234	4			164	61		5
Other comprehensive income	1						1
Net change in parent advances	(418)					(418)
Acquisition of the DCP Midstream Business \| Predecessor	(4,220)
Acquisition of the DCP Midstream Business	(4,220)
Deficit purchase price under carrying value of the Transaction	3,092					3,094	(2)
Proceeds from Issuance of Preferred Limited Partners Units	487	487
Partners Capital Account Acquisitions Issuance Of Units	487					0
Proceeds from issuance of common units, net of offering costs	1,125				92	1,033
Distributions to unitholders	(545)				(120)	(425)
Distributions to noncontrolling interests	(7)							(7)
Ending balance (Predecessor) at Dec. 31, 2017	0
Ending balance at Dec. 31, 2017	7,438	491	$ 0	$ 0	154	6,772	(9)	30
Increase (Decrease) in Partners' Capital [Roll Forward]
Cumulative effect adjustment for Adoption of ASC 606	6	0	0	0	0	6	0	0
Net income	302	37	8	2	164	87		4
Other comprehensive income	1						(1)
Proceeds from Issuance of Preferred Limited Partners Units	261	0	155	106		0
Distributions to unitholders	(706)	(39)	(7)	(2)	(211)	(447)
Distributions to noncontrolling interests	(5)	0	0	0	0	0	0	(5)
Ending balance at Dec. 31, 2018	$ 7,297	$ 489	$ 156	$ 106	$ 107	$ 6,418	$ (8)	$ 29

Consolidated Statements of Changes in Equity (Parenthetical) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Issuance of 28,552,480 common units and 2,550,644 general partner units to DCP Midstream, LLC and affiliates [Member] \| Limited Partners
Issuance of common units (in shares)		28,552,480
Issuance of 28,552,480 common units and 2,550,644 general partner units to DCP Midstream, LLC and affiliates [Member] \| General Partner
Issuance of common units (in shares)		2,550,644
Issuance of 500,000 Series A Preferred Units [Member] \| Series A Preferred Limited Partners [Member]
Sale of Preferred Limited Partnership Units		500,000
Issuance of 6,450,000 Series B Preferred Units [Member] \| Series B Preferred Limited Partners [Member]
Sale of Preferred Limited Partnership Units	6,450,000
Issuance of 4,400,000 Series C Preferred Units [Member] \| Series C Preferred Limited Partners [Member]
Sale of Preferred Limited Partnership Units	4,400,000

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES:
Net income	$ 302	$ 234	$ 94
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	388	379	378
Earnings from unconsolidated affiliates	(370)	(303)	(282)
Distributions from unconsolidated affiliates	441	367	356
Net unrealized (gains) losses on derivative instruments	(108)	28	139
Gain on sale of assets, net	0	34	35
Asset impairments	145	48	0
Loss from financing activities	19	0	0
Other, net	15	32	68
Change in operating assets and liabilities, which (used) provided cash, net of effects of acquisitions:
Accounts receivable	(55)	(194)	(247)
Inventories	(11)	4	21
Accounts payable	(168)	328	199
Increase (Decrease) in Other Operating Assets and Liabilities, Net	64	7	(4)
Net cash provided by operating activities	662	896	645
INVESTING ACTIVITIES:
Capital expenditures	(595)	(375)	(144)
Investments in unconsolidated affiliates	(354)	(148)	(53)
Proceeds from sale of assets	4	132	163
Net cash used in investing activities	(945)	(391)	(34)
FINANCING ACTIVITIES:
Proceeds from debt	5,161	116	3,353
Payments of debt	(4,560)	(811)	(3,628)
Costs incurred to redeem senior notes	(18)	0	0
Proceeds from issuance of preferred limited partner units, net of offering costs	261	487	0
Distributions to preferred limited partners	(46)	0	0
Net change in advances to predecessor from DCP Midstream, LLC	0	418	157
Distributions to limited partners and general partner	(658)	(545)	(483)
Distributions to noncontrolling interests	(5)	(7)	(7)
Other	(7)	(8)	(5)
Net cash provided by (used in) financing activities	128	(350)	(613)
Net change in cash and cash equivalents	(155)	155	(2)
Cash and cash equivalents, beginning of period	156	1	3
Cash and cash equivalents, end of period	$ 1	$ 156	$ 1

Description of Business and Basis of Presentation	12 Months Ended
Description of Business and Basis of Presentation	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation DCP Midstream, LP, with its consolidated subsidiaries, or "us", "we", "our" or the "Partnership" is a Delaware limited partnership formed in 2005 by DCP Midstream, LLC to own, operate, acquire and develop a diversified portfolio of complementary midstream energy assets. Our Partnership includes our Logistics and Marketing and Gathering and Processing segments. For additional information regarding these segments, see Note 21 - Business Segments. Our operations and activities are managed by our general partner, DCP Midstream GP, LP, which in turn is managed by its general partner, DCP Midstream GP, LLC, which we refer to as the General Partner, and which is 100% owned by DCP Midstream, LLC. DCP Midstream, LLC and its subsidiaries and affiliates, collectively referred to as DCP Midstream, LLC, is owned 50% by Phillips 66 and 50% by Enbridge Inc. and its affiliates, or Enbridge. DCP Midstream, LLC directs our business operations through its ownership and control of the General Partner. As of December 31, 2018, DCP Midstream, LLC owned approximately 38.1% of us, including limited partner and general partner interests. The consolidated financial statements include the accounts of the Partnership and all majority-owned subsidiaries where we have the ability to exercise control. Investments in greater than 20% owned affiliates that are not variable interest entities and where we do not have the ability to exercise control, and investments in less than 20% owned affiliates where we have the ability to exercise significant influence, are accounted for using the equity method. The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP. All intercompany balances and transactions have been eliminated in consolidation.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Summary of Significant Accounting Policies [Abstract]

Significant Accounting Policies [Text Block]

2. Summary of Significant Accounting Policies

Use of Estimates - Conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and notes. Although these estimates are based on management’s best available knowledge of current and expected future events, actual results could differ from those estimates.

Cash and Cash Equivalents - We consider investments in highly liquid financial instruments purchased with an original stated maturity of 90 days or less and temporary investments of cash in short-term money market securities to be cash equivalents.

Allowance for Doubtful Accounts - Management estimates the amount of required allowances for the potential non-collectability of accounts receivable generally based upon the number of days past due, past collection experience and consideration of other relevant factors. However, past experience may not be indicative of future collections and therefore additional charges could be incurred in the future to reflect differences between estimated and actual collections.

Inventories - Inventories, which consist primarily of NGLs and natural gas, are recorded at the lower of weighted-average cost or market value. Transportation costs are included in inventory.

Accounting for Risk Management Activities and Financial Instruments - Non-trading energy commodity derivatives are designated as a hedge of a forecasted transaction or future cash flow (cash flow hedge), a hedge of a recognized asset, liability or firm commitment (fair value hedge), or normal purchases or normal sales. The remaining non-trading derivatives, which are related to asset-based activities for which the normal purchase or normal sale exception is not elected, are recorded at fair value in the consolidated balance sheets as unrealized gains or unrealized losses in derivative instruments, with changes in the fair value recognized in the consolidated statements of operations. For each derivative, the accounting method and presentation of gains and losses or revenue and expense in the consolidated statements of operations are as follows:



Classification of Contract	Accounting Method	Presentation of Gains & Losses or Revenue & Expense
Trading Derivatives	Mark-to-market method (a)	Net basis in trading and marketing gains and losses
Non-Trading Derivatives:
Cash Flow Hedge	Hedge method (b)	Gross basis in the same consolidated statements of operations category as the related hedged item

Fair Value Hedge	Hedge method (b)	Gross basis in the same consolidated statements of operations category as the related hedged item

Normal Purchases or Normal Sales	Accrual method (c)	Gross basis upon settlement in the corresponding consolidated statements of operations category based on purchase or sale

Other Non-Trading Derivative Activity	Mark-to-market method (a)	Net basis in trading and marketing gains and losses, net


(a)	Mark-to-market method - An accounting method whereby the change in the fair value of the asset or liability is recognized in the consolidated statements of operations in trading and marketing gains and losses, net during the current period.

(b)

Hedge method - An accounting method whereby the change in the fair value of the asset or liability is recorded in the consolidated balance sheets as unrealized gains or unrealized losses on derivative instruments. For cash flow hedges, there is no recognition in the consolidated statements of operations for the effective portion until the service is provided or the associated delivery impacts earnings. For fair value hedges, the change in the fair value of the asset or liability, as well as the offsetting changes in value of the hedged item, are recognized in the consolidated statements of operations in the same category as the related hedged item.


(c)	Accrual method - An accounting method whereby there is no recognition in the consolidated balance sheets or consolidated statements of operations for changes in fair value of a contract until the service is provided or the associated delivery impacts earnings.

Cash Flow and Fair Value Hedges - For derivatives designated as a cash flow hedge or a fair value hedge, we maintain formal documentation of the hedge. In addition, we formally assess both at the inception of the hedging relationship and on an ongoing basis, whether the hedge contract is highly effective in offsetting changes in cash flows or fair values of hedged items. All components of each derivative gain or loss are included in the assessment of hedge effectiveness, unless otherwise noted.

The fair value of a derivative designated as a cash flow hedge is recorded in the consolidated balance sheets as unrealized gains or unrealized losses on derivative instruments. The change in fair value of the effective portion of a derivative designated as a cash flow hedge is recorded in partners’ equity in accumulated other comprehensive income, or AOCI, and the ineffective portion is recorded in the consolidated statements of operations. During the period in which the hedged transaction impacts earnings, amounts in AOCI associated with the hedged transaction are reclassified to the consolidated statements of operations in the same line item as the item being hedged. Hedge accounting is discontinued prospectively when it is determined that the derivative no longer qualifies as an effective hedge, or when it is probable that the hedged transaction will not occur. When hedge accounting is discontinued because the derivative no longer qualifies as an effective hedge, the derivative is subject to the mark-to-market accounting method prospectively. The derivative continues to be carried on the consolidated balance sheets at its fair value; however, subsequent changes in its fair value are recognized in current period earnings. Gains and losses related to discontinued hedges that were previously accumulated in AOCI will remain in AOCI until the hedged transaction impacts earnings, unless it is probable that the hedged transaction will not occur, in which case, the gains and losses that were previously deferred in AOCI will be immediately recognized in current period earnings.

The fair value of a derivative designated as a fair value hedge is recorded for balance sheet purposes as unrealized gains or unrealized losses on derivative instruments. We recognize the gain or loss on the derivative instrument, as well as the offsetting loss or gain on the hedged item in earnings in the current period. All derivatives designated and accounted for as fair value hedges are classified in the same category as the item being hedged in the results of operations.

Valuation - When available, quoted market prices or prices obtained through external sources are used to determine a contract’s fair value. For contracts with a delivery location or duration for which quoted market prices are not available, fair value is determined based on pricing models developed primarily from historical relationships with quoted market prices and the expected relationship with quoted market prices.

Values are adjusted to reflect the credit risk inherent in the transaction as well as the potential impact of liquidating open positions in an orderly manner over a reasonable time period under current conditions. Changes in market prices and management estimates directly affect the estimated fair value of these contracts. Accordingly, it is reasonably possible that such estimates may change in the near term.

Property, Plant and Equipment - Property, plant and equipment are recorded at historical cost. The cost of maintenance and repairs, which are not significant improvements, are expensed when incurred. Depreciation is computed using the straight-line method over the estimated useful lives of the assets.

Capitalized Interest - We capitalize interest during construction of major projects. Interest is calculated on the monthly outstanding capital balance and ceases in the month that the asset is placed into service. We also capitalize interest on our equity method investments which are devoting substantially all efforts to establishing a new business and have not yet begun planned principal operations. Capitalization ceases when the investee commences planned principal operations. The rates used to calculate capitalized interest are the weighted-average cost of debt, including the impact of interest rate swaps.

Asset Retirement Obligations - Our asset retirement obligations relate primarily to the retirement of various gathering pipelines and processing facilities and obligations related to right-of-way and land easement agreements. We adjust our asset retirement obligation each quarter for any liabilities incurred or settled during the period, accretion expense and any revisions made to the estimated cash flows.

Asset retirement obligations associated with tangible long-lived assets are recorded at fair value in the period in which they are incurred, if a reasonable estimate of fair value can be made, and added to the carrying amount of the associated asset. This additional carrying amount is then depreciated over the life of the asset. The liability is determined using a credit-adjusted risk free interest rate, and accretes due to the passage of time based on the time value of money until the obligation is settled.

Goodwill and Intangible Assets - Goodwill is the cost of an acquisition less the fair value of the net assets of the acquired business. We perform an annual impairment test of goodwill at the reporting unit level during the third quarter, and update the test during interim periods when we believe events or changes in circumstances indicate that we may not be able to recover the carrying value of a reporting unit. We primarily use a discounted cash flow analysis, supplemented by a market approach analysis, to perform the assessment. Key assumptions in the analysis include the use of an appropriate discount rate, terminal year multiples, and estimated future cash flows including an estimate of operating and general and administrative costs. In estimating cash flows, we incorporate current market information, as well as historical and other factors, into our forecasted commodity prices. A period of lower commodity prices may adversely affect our estimate of future operating results, which could result in future goodwill and intangible assets impairment due to the potential impact on our operations and cash flows.

Intangible assets consist of customer contracts, including commodity purchase, transportation and processing contracts, and related relationships. These intangible assets are amortized on a straight-line basis over the period of expected future benefit. Intangible assets are removed from the gross carrying amount and the total of accumulated amortization in the period in which they become fully amortized.

Investments in Unconsolidated Affiliates - We use the equity method to account for investments in greater than 20% owned affiliates.

We evaluate our investments in unconsolidated affiliates for impairment whenever events or changes in circumstances indicate that the carrying value of such investments may have experienced a decline in value. When there is evidence of loss in value that is other than temporary, we compare the estimated fair value of the investment to the carrying value of the investment to determine whether impairment has occurred. We assess the fair value of our investments in unconsolidated affiliates using commonly accepted techniques, and may use more than one method, including, but not limited to, recent third party comparable sales and discounted cash flow models. If the estimated fair value is less than the carrying value, the excess of the carrying value over the estimated fair value is recognized as an impairment loss.

Long-Lived Assets - We periodically evaluate whether the carrying value of long-lived assets, including intangible assets, has been impaired when circumstances indicate the carrying value of those assets may not be recoverable. This evaluation is based on undiscounted cash flow projections. The carrying amount is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. We consider various factors when determining if these assets should be evaluated for impairment, including but not limited to:


•	significant adverse change in legal factors or business climate;


•	a current-period operating or cash flow loss combined with a history of operating or cash flow losses, or a projection or forecast that demonstrates continuing losses associated with the use of a long-lived asset;


•	an accumulation of costs significantly in excess of the amount originally expected for the acquisition or construction of a long-lived asset;


•	significant adverse changes in the extent or manner in which an asset is used, or in its physical condition;


•	a significant adverse change in the market value of an asset; or


•	a current expectation that, more likely than not, an asset will be sold or otherwise disposed of before the end of its estimated useful life.

If the carrying value is not recoverable, the impairment loss is measured as the excess of the asset’s carrying value over its fair value. We assess the fair value of long-lived assets using commonly accepted techniques, and may use more than one method, including, but not limited to, recent third party comparable sales and discounted cash flow models. Significant changes in market conditions resulting from events such as the condition of an asset or a change in management’s intent to utilize the asset would generally require management to reassess the cash flows related to the long-lived assets. A period of lower commodity prices may adversely affect our estimate of future operating results, which could result in future impairment due to the potential impact on our operations and cash flows.

Unamortized Debt Discount and Expense - Discounts and expenses incurred with the issuance of long-term debt are amortized over the term of the debt using the effective interest method. The discounts and unamortized expenses are recorded on the consolidated balance sheets within the carrying amount of long-term debt.

Noncontrolling Interest - Noncontrolling interest represents any third party or affiliate interest in non-wholly owned entities that we consolidate. For financial reporting purposes, the assets and liabilities of these entities are consolidated with those of our own, with any third party or affiliate interest in our consolidated balance sheet amounts shown as noncontrolling interest in equity. Distributions to and contributions from noncontrolling interests represent cash payments to and cash contributions from, respectively, such third party and affiliate investors.

Revenue Recognition - Our operating revenues are primarily derived from the following activities:


•	sales of natural gas, NGLs and condensate;


•	services related to gathering, compressing, treating, and processing natural gas; and


•	services related to transportation and storage of natural gas and NGLs.

Sales of natural gas, NGLs and condensate - We sell our commodities to a variety of customers ranging from large, multi-national petrochemical and refining companies to regional retail propane distributors. We recognize revenue from commodity sales at the point in time when control is obtained by the customer. Generally, the transaction price is determined at the time of each delivery as the variability of commodity pricing is resolved. Customers usually pay monthly based on the products purchased the previous month.

Sales of natural gas, NGLs and condensate include physical sales contracts which qualify as financial derivative instruments, and buy-sell and exchange transactions which involve purchases and sales of inventory with the same counterparty that are legally contingent or in contemplation of one another as a single transaction on a combined net basis. Neither of these types of arrangements are contracts with customers within the scope of FASB ASU 2014-09 Revenue from Contracts with Customers, or "Topic 606".

Gathering, compressing, treating and processing natural gas - For natural gas gathering and processing activities, we receive either fees and/or a percentage of proceeds from commodity sales as payment for these services, depending on the type of contract. For gathering and processing agreements within the scope of Topic 606, we recognize the revenue associated with our services when the gas is gathered, treated or processed at our facilities. Under fee-based contracts, we receive a fee for our services based on throughput volumes. Under percent-of-proceeds contracts, we receive either an agreed upon percentage of the actual proceeds received from our sale of the residue natural gas and NGLs or an agreed upon percentage based on index related prices for the natural gas and NGLs. Our percent-of-proceeds contracts may also include a fee-based component.

Transportation and storage - Revenue from transportation and storage agreements is recognized based on contracted volumes transported and stored in the period the services are provided.

Our service contracts generally have terms that extend beyond one year, and are recognized over time. The performance obligation for most of our service contracts encompasses a series of distinct services performed on discrete daily quantities of natural gas or NGLs for purposes of allocating variable consideration and recognizing revenue while the customer simultaneously receives and consumes the benefits of the services provided. Revenue is recognized over time consistent with the transfer of goods or services over time to the customer based on daily volumes delivered. Consideration is generally variable, and the transaction price cannot be determined at the inception of the contract, because the volume of natural gas or NGLs for which the service is provided is only specified on a daily or monthly basis. The transaction price is determined at the time the service is provided and the uncertainty is resolved. Customers usually pay monthly based on the services performed the previous month.

Purchase arrangements - Under purchase arrangements, we purchase natural gas at either the wellhead or the tailgate of a plant. These purchase arrangements represent an arrangement with a supplier and are recorded in “Purchases and related costs”. Often, we earn fees for services performed prior to taking control of the product in these arrangements and service revenue is recorded for these fees. Revenue generated from the sale of product obtained in these purchase arrangements are reported as “Sales of natural gas, NGLs and condensate” on the consolidated statements of operations and are recognized on a gross basis as we purchase and take control of the product prior to sale and are the principal in the transaction.

Practical expedients - We apply certain practical expedients in Topic 606 and do not disclose information about transaction prices allocated to remaining performance obligations that have original expected durations of one year or less, nor do we disclose information about transaction prices allocated to remaining performance obligations if the variable consideration is allocated entirely to a wholly unsatisfied performance obligation

Contract liabilities - We have contracts with customers whereby the customer reimburses us for costs to construct certain connections to our operating assets. These agreements are typically entered into in contemplation with gathering and processing agreements and transportation agreements with customers, and are part of the consideration of the contract. We previously accounted for these arrangements as a reduction to the cost basis of our long-lived assets which were amortized as a reduction to depreciation expense over the estimated useful life of the related assets. Under Topic 606, we record these payments as deferred revenue which are amortized into revenue over the expected contract term.

Purchases and related costs - Purchases and related costs primarily includes (i) the cost of purchased commodities, including NGLs, natural gas and condensate, and (ii) fees incurred for transportation and fractionation of commodities.

Significant Customers - There were no third party customers that accounted for more than 10% of total operating revenues for the years ended December 31, 2018, 2017 and 2016. We had significant transactions with affiliates for the years ended December 31, 2018, 2017 and 2016. See Note 6, Agreements and Transactions with Related Parties and Affiliates.

Environmental Expenditures - Environmental expenditures are expensed or capitalized as appropriate, depending upon the future economic benefit. Expenditures that relate to an existing condition caused by past operations and that do not generate current or future revenue are expensed. Liabilities for these expenditures are recorded on an undiscounted basis when environmental assessments and/or clean-ups are probable and the costs can be reasonably estimated.

Equity-Based Compensation — Liability classified equity-based compensation cost is remeasured at each reporting date at fair value, based on the closing security price, and is recognized as expense over the requisite service period. Compensation expense for awards with graded vesting provisions is recognized on a straight-line basis over the requisite service period of each separately vesting portion of the award.

Income Taxes - We are structured as a master limited partnership which is a pass-through entity for federal income tax purposes. We owned a corporation that filed its own federal and state corporate income tax returns, which we elected to convert to a limited liability company in 2016. Our income tax expense includes certain jurisdictions, including state, local, franchise and margin taxes of the master limited partnership and subsidiaries. We follow the asset and liability method of accounting for income taxes. Under this method, deferred income taxes are recognized for the tax consequences of temporary differences between the financial statement carrying amounts and the tax basis of the assets and liabilities. Our taxable income or loss, which may vary substantially from the net income or loss reported in the consolidated statements of operations, is proportionately included in the federal income tax returns of each partner.

Net Income or Loss per Limited Partner Unit - Basic and diluted net income or loss per limited partner unit, or LPU, is calculated by dividing net income or loss allocable to limited partners, by the weighted-average number of outstanding LPUs during the period using the two-class method. Diluted net income or loss per limited partner unit is computed based on the weighted average number of limited partner units, plus the effect of dilutive potential units outstanding during the period.

New Accounting Pronouncements

12 Months Ended

Dec. 31, 2018

New Accounting Pronouncements, Policy [Abstract]

New Accounting Pronouncements

Financial Accounting Standards Board, or FASB, Accounting Standards Update, or ASU, 2016-15 “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” or ASU 2016-15 - In August 2016, the FASB issued ASU 2016-15, which amends certain cash flow statement classification guidance. We adopted the ASU on January 1, 2018 and it has not had any impact on our consolidated cash flows.

FASB ASU, 2016-13 "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" or ASU 2016-13 - In June 2016, the FASB issued ASU 2016-13, which amends current measurement techniques used to estimate credit losses for financial assets. This ASU is effective for interim and annual reporting periods beginning after December 15, 2019, with the option to early adopt for financial statements that have not been issued. We are currently evaluating the potential impact this standard will have on our consolidated financial statements and related disclosures.

FASB ASU, 2016-02 “Leases (Topic 842),” or ASU 2016-02 - In February 2016, the FASB issued ASU 2016-02, which requires lessees to recognize a lease liability on a discounted basis and the right of use of a specified asset at the commencement date for all leases. This ASU is effective for interim and annual reporting periods beginning after December 15, 2018, with the option to early adopt for financial statements that have not been issued.

We adopted Topic 842 on January 1, 2019 using the modified retrospective approach without application to prior periods. We elected the package of practical expedients permitted under the transition guidance within the new standard, and the land easement practical expedient, allowing us to carry forward our current accounting treatment for land easements on existing agreements. Policy elections made as part of our adoption of Topic 842 include (a) not recognizing lease assets or liabilities when lease terms are less than twelve months, and (b) for agreements that contain both lease and non-lease components, combining these components together and accounting for them as a single lease. Our leasing activity primarily consists of transportation agreements, office space, vehicles and equipment. Topic 842 will result in changes to the way we recognize, present and disclose our operating leases in our consolidated financial statements, including the recognition of a lease liability and an offsetting right-of-use asset in our consolidated balance sheets for our operating leases (with the exception of short-term leases excluded by practical expedient). However, this change will not have any impact on our net income (loss) or cash flows. See Note 19 - Commitments and Contingent Liabilities for a summary of our future minimum rental payments under our various operating leases.

FASB ASU 2014-09 “Revenue from Contracts with Customers" or ASU 2014-09 and related interpretations and amendments - In May 2014, the FASB issued ASU 2014-09, which supersedes the revenue recognition requirements of Accounting Standards Codification Topic 605 “Revenue Recognition.” We adopted this ASU on January 1, 2018 using the modified retrospective method for contracts that were not completed as of the date of adoption. Under this method, the comparative information has not been restated and continues to be reported under the accounting standards in effect for those prior periods. Under the new standard, revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration the entity expects to receive in exchange for those goods or services. We recognized the initial cumulative effect of applying this ASU as an adjustment to the opening balance of total partners’ equity.

In accordance with the new revenue standard requirements, the impact of adoption on our consolidated statement of operations was as follows:



		Year Ended December 31, 2018
		As Reported		Effect of Change			Presentation Without Adoption of ASC 606
	(millions)
Statement of Operations
Operating revenues
Sales of natural gas, NGLs and condensate		$	7,764	$	(148	)	$	7,912
Transportation, processing and other		$	489	$	(165	)	$	654

Costs and expenses
Purchases and related costs		$	7,123	$	(313	)	$	7,436

Net income		$	302	$	—		$	302

Revenue Recognition

12 Months Ended

Dec. 31, 2018

Revenue Recognition [Abstract]

Revenue from External Customers by Products and Services [Table Text Block]

Revenue Recognition

We disaggregate our revenue from contracts with customers by type of contract for each of our reportable segments, as we believe it best depicts the nature, timing and uncertainty of our revenue and cash flows. The following tables set forth our revenue by those categories:



	Year Ended December 31, 2018
	Gathering and Processing		Logistics and Marketing			Eliminations			Total
	(millions)
Sales of natural gas	$	1,955	$	2,325		$	(1,752	)	$	2,528
Sales of NGLs and condensate (a)	3,437		6,692			(3,283		)	6,846
Transportation, processing and other	432		57			—			489
Trading and marketing losses, net (b)	19		(60		)	—			(41		)
Total operating revenues	$	5,843	$	9,014		$	(5,035	)	$	9,822

(a) Includes $4,347 million of revenues from physical sales contracts and buy-sell exchange transactions in our logistics and marketing segment, which are not within the scope of Topic 606.

(b) Not within the scope of Topic 606.

The revenue expected to be recognized in the future related to performance obligations that are not satisfied is approximately $219 million as of December 31, 2018. Our remaining performance obligations primarily consist of minimum volume commitment fee arrangements and are expected to be recognized through 2028 with a weighted average remaining life of 5 years as of December 31, 2018. As a practical expedient permitted by ASC 606, this amount excludes variable consideration as well as remaining performance obligations that have original expected durations of one year or less, as applicable. Our remaining performance obligations also exclude estimates of variable rate escalation clauses in our contracts with customers.

Agreements and Transactions with Affiliates

12 Months Ended

Dec. 31, 2018

Agreements and Transactions with Affiliates

DCP Midstream, LLC

Services Agreement and Other General and Administrative Charges

Under the Services Agreement, we are required to reimburse DCP Midstream, LLC for costs, expenses, and expenditures incurred or payments made on our behalf for general and administrative functions including, but not limited to, legal, accounting, compliance, treasury, insurance administration and claims processing, risk management, health, safety and environmental, information technology, human resources, benefit plan maintenance and administration, credit, payroll, internal audit, taxes and engineering, as well as salaries and benefits of seconded employees, insurance coverage and claims, capital expenditures, maintenance and repair costs and taxes. There is no limit on the reimbursements we make to DCP Midstream, LLC under the Services Agreement for costs, expenses and expenditures incurred or payments made on our behalf. The following table summarizes employee related costs that were charged by DCP Midstream, LLC to the Partnership that are included in the consolidated statements of operations:



		Year Ended December 31,
		2018		2017		2016
	(millions)
Employee related costs charged by DCP Midstream, LLC
Operating and maintenance expense		$	209	$	197	$	206
General and administrative expense		$	187	$	182	$	197

Phillips 66 and its Affiliates

We sell a portion of our residue gas and NGLs to and purchase NGLs from Phillips 66 and its respective affiliates. We anticipate continuing to sell commodities to and purchase commodities from Phillips 66 and its affiliates in the ordinary course of business.

Enbridge and its Affiliates

We sell NGLs to and purchase NGLs from Enbridge and its affiliates. We anticipate continuing to sell commodities to and purchase commodities from Enbridge and its affiliates in the ordinary course of business.

Unconsolidated Affiliates

We have entered into 10 to 15-year transportation agreements, with Sand Hills Pipeline, LLC, or Sand Hills, Southern Hills Pipeline, LLC, or Southern Hills, Front Range Pipeline LLC, or Front Range, Texas Express Pipeline LLC, or Texas Express and Gulf Coast Express Pipeline, LLC, or Gulf Coast. Under the terms of these agreements, which expire between 2028 and 2029, we have committed to transport minimum throughput volumes at rates defined in each of the pipelines’ respective tariffs.

We sell a portion of our residue gas and NGLs to, purchase natural gas and other NGL products from, and provide gathering and transportation services to other unconsolidated affiliates. We anticipate continuing to purchase and sell commodities and provide services to unconsolidated affiliates in the ordinary course of business.

Under the terms of the Sand Hills LLC Agreement and the Southern Hills LLC Agreement, or the Sand Hills and Southern Hills LLC Agreements, Sand Hills and Southern Hills are required to reimburse us for any direct costs or expenses (other than general and administration services) which we incur on behalf of Sand Hills and Southern Hills. Additionally, Sand Hills and Southern Hills each pay us an annual service fee of $5 million, for centralized corporate functions provided by us as operator of Sand Hills and Southern Hills, including legal, accounting, cash management, insurance administration and claims processing, risk management, health, safety and environmental, information technology, human resources, credit, payroll, taxes and engineering. Except with respect to the annual service fee, there is no limit on the reimbursements Sand Hills and Southern Hills make to us under the Sand Hills and Southern Hills LLC Agreements for other expenses and expenditures which we incur on behalf of Sand Hills or Southern Hills.

Summary of Transactions with Affiliates

The following table summarizes our transactions with affiliates:



		Year Ended December 31,
		2018		2017		2016
	(millions)
Phillips 66 (including its affiliates):
Sales of natural gas, NGLs and condensate to affiliates		$	1,534	$	1,172	$	909
Purchases and related costs from affiliates		$	138	$	30	$	18
Operating and maintenance and general administrative expenses		$	13	$	2	$	2
Enbridge (including its affiliates):
Sales of natural gas, NGLs and condensate to affiliates		$	11	$	48	$	—
Purchases and related costs from affiliates		$	35	$	43	$	33
Operating and maintenance and general administrative expenses		$	—	$	2	$	4
Unconsolidated affiliates:
Sales of natural gas, NGLs and condensate to affiliates		$	65	$	54	$	43
Transportation, processing, and other to affiliates		$	6	$	5	$	5
Purchases and related costs from affiliates		$	723	$	504	$	432

We had balances with affiliates as follows:



	December 31, 2018		December 31, 2017
	(millions)
Phillips 66 (including its affiliates):
Accounts receivable	$	145	$	156
Accounts payable	$	22	$	6
Other assets	$	—	$	—
Enbridge (including its affiliates):
Accounts receivable	$	—	$	11
Accounts payable	$	2	$	9
Unconsolidated affiliates:
Accounts receivable	$	21	$	24
Accounts payable	$	72	$	53
Other assets	$	—	$	4

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

A summary of property, plant and equipment by classification is as follows:



	Depreciable Life	December 31, 2018			December 31, 2017
		(millions)
Gathering and transmission systems	20 — 50 Years	$	8,492		$	8,473
Processing, storage and terminal facilities	35 — 60 Years	5,194			5,128
Other	3 — 30 Years	568			557
Construction work in progress		470			374
Property, plant and equipment		14,724			14,532
Accumulated depreciation		(5,589		)	(5,549		)
Property, plant and equipment, net		$	9,135		$	8,983

Interest capitalized on construction projects was $19 million, $7 million and less than $1 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Depreciation expense was $378 million, $367 million and $366 million for the years ended December 31, 2018, 2017 and 2016 respectively.

Asset Retirement Obligations

We identified various assets as having an indeterminate life, for which there is no requirement to establish a fair value for future retirement obligations associated with such assets. These assets include certain pipelines, gathering systems and processing facilities. A liability for these asset retirement obligations will be recorded only if and when a future retirement obligation with a determinable life is identified. These assets have an indeterminate life because they are owned and will operate for an indeterminate future period when properly maintained. Additionally, if the portion of an owned plant containing asbestos were to be modified or dismantled, we would be legally required to remove the asbestos. We currently have no plans to take actions that would require the removal of the asbestos in these assets. Accordingly, the fair value of the asset retirement obligation related to this asbestos cannot be estimated and no obligation has been recorded.

The following table summarizes changes in the asset retirement obligations included in our balance sheets:



	December 31,
	2018 (a)		2017 (a)
	(millions)
Balance, beginning of period	$	126	$	124
Accretion expense	8		8
Change in ARO Estimate	6		(6		)
Balance, end of period	$	140	$	126

(a) Asset retirement obligations are included in other long-term liabilities in the consolidated balance sheets. Accretion expense is recorded within operating and maintenance expense in our consolidated statement of operations. Accretion expense for the year ended December 31, 2016 was $7 million.

Goodwill

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill

We performed our annual goodwill assessment during the third quarter of 2018 at the reporting unit level, which is conducted by assessing whether (i) the components of our operating segments constitute businesses for which discrete financial information is available, (ii) segment management regularly reviews the operating results of those components and (iii) whether the economic and regulatory characteristics are similar. As a result of our assessment, we concluded that the fair value of goodwill substantially exceeded its carrying value in our North reporting unit, the only reporting unit allocated goodwill included within our Gathering and Processing reportable segment, and in our Marysville reporting unit included within our Logistics and Marketing reportable segment. For our Wholesale Propane reporting unit, which is included in our Logistics and Marketing reportable segment, the fair value exceeded the carrying value (including approximately $37 million of allocated goodwill) by approximately 10%. We concluded that the entire amount of goodwill disclosed on the consolidated balance sheet is recoverable.

We primarily used a discounted cash flow analysis, supplemented by a market approach analysis, to perform our goodwill assessment. Key assumptions in the analysis include the use of an appropriate discount rate, terminal year multiples, and estimated future cash flows, including an estimate of operating and general and administrative costs. In estimating cash flows, we incorporate current market information (including forecasted volumes and commodity prices), as well as historical and other factors. If actual results are not consistent with our assumptions and estimates, or our assumptions and estimates change due to new information, we may be exposed to goodwill impairment charges, which would be recognized in the period in which the carrying value exceeds fair value.

We expect that the fair value of our Wholesale Propane reporting unit will continue to exceed its carrying value so long as our estimate of future cash flows and the market valuation remain consistent with current levels. A continued period of volatile propane prices could result in further deterioration of market multiples, comparable sales transactions prices, weighted average costs of capital, and our cash flow estimates. Changes to any one or combination of these factors, would result in changes to the reporting unit fair values discussed above which could lead to future impairment charges. Such potential impairment could have a material effect on our results of operations.

The carrying amount of goodwill in each of our reportable segments was as follows:




	December 31, 2018						December 31, 2017
	(millions)
	Gathering and Processing		Logistics and Marketing		Total		Gathering and Processing			Logistics and Marketing		Total
Balance, beginning of period	$	159	$	72	$	231	$	164		$	72	$	236
Dispositions	—		—		—		(5		)	—		(5		)
Balance, end of period	$	159	$	72	$	231	$	159		$	72	$	231

Intangible assets consist of customer contracts, including commodity purchase, transportation and processing contracts and related relationships. The gross carrying amount and accumulated amortization of these intangible assets are included in the accompanying consolidated balance sheets as intangible assets, net, and are as follows:



	December 31,			December 31,
	2018			2017
	(millions)
Gross carrying amount	$	410		$	410
Accumulated amortization	(170		)	(161		)
Accumulated impairment	(143		)	(143		)
Intangible assets, net	$	97		$	106

We recorded amortization expense of $9 million, $10 million and $12 million for the years ended December 31, 2018, 2017, and 2016, respectively. As of December 31, 2018, the remaining amortization periods ranged from approximately 3 years to 17 years, with a weighted-average remaining period of approximately 12 years.

Estimated future amortization for these intangible assets is as follows:



Estimated Future Amortization
(millions)
2019	$	9
2020	9
2021	9
2022	9
2023	8
Thereafter	53
Total	$	97

Investments in Unconsolidated Affiliates

12 Months Ended

Dec. 31, 2018

Equity Method Investments and Joint Ventures [Abstract]

Investments in Unconsolidated Affiliates

The following table summarizes our investments in unconsolidated affiliates:



		Carrying Value as of
	Percentage Ownership	December 31, 2018		December 31, 2017
		(millions)
DCP Sand Hills Pipeline, LLC	66.67%	$	1,791	$	1,633
DCP Southern Hills Pipeline, LLC	66.67%	728		739
Discovery Producer Services LLC	40.00%	344		362
Front Range Pipeline LLC	33.33%	175		165
Texas Express Pipeline LLC	10.00%	95		90
Gulf Coast Express Pipeline LLC	25.00%	146		—
Mont Belvieu Enterprise Fractionator	12.50%	24		23
Panola Pipeline Company, LLC	15.00%	23		24
Mont Belvieu 1 Fractionator	20.00%	10		10
Other	Various	4		4
Total investments in unconsolidated affiliates		$	3,340	$	3,050

The following table represents the excess (deficit) of the carrying amount of the investment over (under) the underlying equity of our investments in unconsolidated affiliates as of December 31, 2018 and 2017:



	Excess (deficit) of Carrying Value over (under) Underlying Equity in Unconsolidated Affiliates
	December 31, 2018			December 31, 2017
	(millions)
DCP Sand Hills Pipeline, LLC	$	634		$	648
Discovery Producer Services LLC	(15		)	(18		)
DCP Southern Hills Pipeline, LLC	142			145
Front Range Pipeline LLC	4			4
Texas Express Pipeline LLC	3			3
Mont Belvieu 1 Fractionator	—			(1		)

Carrying amounts in excess or deficit of the underlying equity of our unconsolidated affiliates are amortized over the life of the underlying long-lived assets of the affiliate.

Earnings from investments in unconsolidated affiliates were as follows:



		Year Ended December 31,
		2018		2017		2016
	(millions)
DCP Sand Hills Pipeline, LLC		$	223	$	148	110
DCP Southern Hills Pipeline, LLC		68		47		44
Discovery Producer Services LLC		8		61		73
Front Range Pipeline LLC		24		17		19
Texas Express Pipeline LLC		19		9		9
Mont Belvieu Enterprise Fractionator		10		13		16
Mont Belvieu 1 Fractionator		16		6		9
Other		2		2		2
Total earnings from unconsolidated affiliates		$	370	$	303	$	282

The following tables summarize the combined financial information of our investments in unconsolidated affiliates:



	Year Ended December 31,
	2018		2017		2016
	(millions)
Statements of operations:
Operating revenue	$	1,560	$	1,397	$	1,311
Operating expenses	$	613	$	647	$	539
Net income	$	945	$	747	$	768



	December 31, 2018			December 31, 2017
	(millions)
Balance sheets:
Current assets	$	411		$	244
Long-term assets	6,359			5,319
Current liabilities	(424		)	(196		)
Long-term liabilities	(221		)	(200		)
Net assets	$	6,125		$	5,167

Fair Value Measurement

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurement

Determination of Fair Value

Below is a general description of our valuation methodologies for derivative financial assets and liabilities which are measured at fair value. Fair values are generally based upon quoted market prices or prices obtained through external sources, where available. If listed market prices or quotes are not available, we determine fair value based upon a market quote, adjusted by other market-based or independently sourced market data such as historical commodity volatilities, crude oil future yield curves, and/or counterparty specific considerations. These adjustments result in a fair value for each asset or liability under an “exit price” methodology, in line with how we believe a marketplace participant would value that asset or liability. Fair values are adjusted to reflect the credit risk inherent in the transaction as well as the potential impact of liquidating open positions in an orderly manner over a reasonable time period under current conditions. These adjustments may include amounts to reflect counterparty credit quality, the effect of our own creditworthiness, and/or the liquidity of the market.

•

Counterparty credit valuation adjustments are necessary when the market price of an instrument is not indicative of the fair value as a result of the credit quality of the counterparty. Generally, market quotes assume that all counterparties have near zero, or low, default rates and have equal credit quality. Therefore, an adjustment may be necessary to reflect the credit quality of a specific counterparty to determine the fair value of the instrument. We record counterparty credit valuation adjustments on all derivatives that are in a net asset position as of the measurement date in accordance with our established counterparty credit policy, which takes into account any collateral margin that a counterparty may have posted with us as well as any letters of credit that they have provided.

•

Entity valuation adjustments are necessary to reflect the effect of our own credit quality on the fair value of our net liability positions with each counterparty. This adjustment takes into account any credit enhancements, such as collateral margin we may have posted with a counterparty, as well as any letters of credit that we have provided. The methodology to determine this adjustment is consistent with how we evaluate counterparty credit risk, taking into account our own credit rating, current credit spreads, as well as any change in such spreads since the last measurement date.

•

Liquidity valuation adjustments are necessary when we are not able to observe a recent market price for financial instruments that trade in less active markets for the fair value to reflect the cost of exiting the position. Exchange traded contracts are valued at market value without making any additional valuation adjustments and, therefore, no liquidity reserve is applied. For contracts other than exchange traded instruments, we mark our positions to the midpoint of the bid/ask spread, and record a liquidity reserve based upon our total net position. We believe that such practice results in the most reliable fair value measurement as viewed by a market participant.

We manage our derivative instruments on a portfolio basis and the valuation adjustments described above are calculated on this basis. We believe that the portfolio level approach represents the highest and best use for these assets as there are benefits inherent in naturally offsetting positions within the portfolio at any given time, and this approach is consistent with how a market participant would view and value the assets and liabilities. Although we take a portfolio approach to managing these assets/liabilities, in order to reflect the fair value of any one individual contract within the portfolio, we allocate all valuation adjustments down to the contract level, to the extent deemed necessary, based upon either the notional contract volume, or the contract value, whichever is more applicable.

The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. While we believe that our valuation methods are appropriate and consistent with other market participants, we recognize that the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. We review our fair value policies on a regular basis taking into consideration changes in the marketplace and, if necessary, will adjust our policies accordingly. See Note 13 - Risk Management and Hedging Activities.

Valuation Hierarchy

Our fair value measurements are grouped into a three-level valuation hierarchy and are categorized in their entirety in the same level of the fair value hierarchy as the lowest level input that is significant to the entire measurement. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The three levels are defined as follows.


•	Level 1 — inputs are unadjusted quoted prices for identical assets or liabilities in active markets.


•	Level 2 — inputs include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument.


•	Level 3 — inputs are unobservable and considered significant to the fair value measurement.

A financial instrument’s categorization within the hierarchy is based upon the level of judgment involved in the most significant input in the determination of the instrument’s fair value. Following is a description of the valuation methodologies used as well as the general classification of such instruments pursuant to the hierarchy.

Commodity Derivative Assets and Liabilities

We enter into a variety of derivative financial instruments, which may include exchange traded instruments (such as New York Mercantile Exchange, or NYMEX, crude oil or natural gas futures) or over-the-counter, or OTC, instruments (such as natural gas contracts, crude oil or NGL swaps). The exchange traded instruments are generally executed with a highly rated broker dealer serving as the clearinghouse for individual transactions.

Our activities expose us to varying degrees of commodity price risk. To mitigate a portion of this risk and to manage commodity price risk related primarily to owned natural gas storage and pipeline assets, we engage in natural gas asset based trading and marketing, and we may enter into natural gas and crude oil derivatives to lock in a specific margin when market conditions are favorable. A portion of this may be accomplished through the use of exchange traded derivative contracts. Such instruments are generally classified as Level 1 since the value is equal to the quoted market price of the exchange traded instrument as of our balance sheet date, and no adjustments are required. Depending upon market conditions and our strategy we may enter into exchange traded derivative positions with a significant time horizon to maturity. Although such instruments are exchange traded, market prices may only be readily observable for a portion of the duration of the instrument. In order to calculate the fair value of these instruments, readily observable market information is utilized to the extent it is available; however, in the event that readily observable market data is not available, we may interpolate or extrapolate based upon observable data. In instances where we utilize an interpolated or extrapolated value, and it is considered significant to the valuation of the contract as a whole, we would classify the instrument within Level 3.

We also engage in the business of trading energy related products and services, which exposes us to market variables and commodity price risk. We may enter into physical contracts or financial instruments with the objective of realizing a positive margin from the purchase and sale of these commodity-based instruments. We may enter into derivative instruments for NGLs or other energy related products, primarily using the OTC derivative instrument markets, which are not as active and liquid as exchange traded instruments. Market quotes for such contracts may only be available for short dated positions (up to six months), and an active market itself may not exist beyond such time horizon. Contracts entered into with a relatively short time horizon for which prices are readily observable in the OTC market are generally classified within Level 2. Contracts with a longer time horizon, for which we internally generate a forward curve to value such instruments, are generally classified within Level 3. The internally generated curve may utilize a variety of assumptions including, but not limited to, data obtained from third-party pricing services, historical and future expected relationship of NGL prices to crude oil prices, the knowledge of expected supply sources coming online, expected weather trends within certain regions of the United States, and the future expected demand for NGLs.

Each instrument is assigned to a level within the hierarchy at the end of each financial quarter depending upon the extent to which the valuation inputs are observable. Generally, an instrument will move toward a level within the hierarchy that requires a lower degree of judgment as the time to maturity approaches, and as the markets in which the asset trades will likely become more liquid and prices more readily available in the market, thus reducing the need to rely upon our internally developed assumptions. However, the level of a given instrument may change, in either direction, depending upon market conditions and the availability of market observable data.

Nonfinancial Assets and Liabilities

We utilize fair value to perform impairment tests as required on our property, plant and equipment, goodwill, equity investments in unconsolidated affiliates, and intangible assets. Assets and liabilities acquired in third party business combinations are recorded at their fair value as of the date of acquisition. The inputs used to determine such fair value are primarily based upon internally developed cash flow models and would generally be classified within Level 3 in the event that we were required to measure and record such assets at fair value within our consolidated financial statements. Additionally, we use fair value to determine the inception value of our asset retirement obligations. The inputs used to determine such fair value are primarily based upon costs incurred historically for similar work, as well as estimates from independent third parties for costs that would be incurred to restore leased property to the contractually stipulated condition, and would generally be classified within Level 3.

During the year ended December 31, 2018, we recognized impairments of property, plant and equipment of $145 million for a portion of a specific asset group within the Midcontinent region and a specific asset group in the South region of the Gathering and Processing segment. We considered alternate long-term strategies for the specific portion of the asset group within our Midcontinent region while we projected continuing future losses associated with the use of the asset group within our South region. As it was determined there would be a significant repurposing of the specific portion of the asset group within the Midcontinent region and projected continuing future losses from the asset group within the South region, we determined that a triggering event occurred during the fourth quarter of 2018 requiring further analysis.

The net book value of the assets exceeded the undiscounted cash flows, therefore a fair value calculation was required. Our impairment determinations involved significant assumptions and judgments. We estimated the fair value of future cash flows by forecasting the useful lives of the assets, future commodity prices, volumes, operating costs and selecting the discount rate that reflected the risk inherent in future cash flows. Differing assumptions regarding any of these inputs could have a significant effect on the various valuations. As such, the fair value measurements utilized within these models are classified as non-recurring Level 3 measurements in the fair value hierarchy because they are not observable from objective sources.

There were no other impairment indicators which existed in other assets or asset groups requiring additional impairment analyses.

During the year ended December 31, 2017, we recognized impairments of property, plant and equipment, intangible assets and investment in unconsolidated affiliates of $48 million in our consolidated statement of operations. The Partnership’s management considered alternate long-term strategies for the specific asset group within our South Region. As it was determined there would be a significant repurposing of the asset, management of the Partnership determined that a triggering event occurred during the third quarter 2017, which resulted in the impairment.

The following table presents the carrying value of assets measured at fair value on a non-recurring basis, by consolidated balance sheet caption and by valuation hierarchy, as of and for the years ended December 31, 2018 and 2017.



	December 31, 2018				December 31, 2017
	Net Carrying Value		Asset Impairments		Net Carrying Value		Asset Impairments
	Net Carrying Value		Asset Impairments		Net Carrying Value		Asset Impairments
	(millions)
Property, plant and equipment	$	15	$	145	$	14	$	26
Intangible assets	—		—		11		21
Investment in unconsolidated affiliates	—		—		1		1
Total impairments	$	15	$	145	$	26	$	48

The following table presents the financial instruments carried at fair value as of December 31, 2018 and December 31, 2017, by consolidated balance sheet caption and by valuation hierarchy, as described above:



	December 31, 2018												December 31, 2017
	Level 1			Level 2			Level 3			Total Carrying Value			Level 1			Level 2			Level 3			Total Carrying Value
	(millions)
Current assets:
Commodity derivatives (a)	$	62		$	32		$	14		$	108		$	10		$	17		$	3		$	30
Short-term investments (b)	$	—		$	—		$	—		$	—		$	156		$	—		$	—		$	156
Long-term assets:
Commodity derivatives (c)	$	4		$	2		$	2		$	8		$	1		$	1		$	1		$	3
Current liabilities:
Commodity derivatives (d)	$	(39	)	$	(52	)	$	—		$	(91	)	$	(29	)	$	(34	)	$	(13	)	$	(76	)
Long-term liabilities:
Commodity derivatives (e)	$	(1	)	$	(5	)	$	(2	)	$	(8	)	$	(3	)	$	(11	)	$	(1	)	$	(15	)


(a)	Included in current unrealized gains on derivative instruments in our consolidated balance sheets.


(b)	Includes short-term money market securities included in cash and cash equivalents in our consolidated balance sheets.


(c)	Included in long-term unrealized gains on derivative instruments in our consolidated balance sheets.


(d)	Included in current unrealized losses on derivative instruments in our consolidated balance sheets.


(e)	Included in long-term unrealized losses on derivative instruments in our consolidated balance sheets.

Changes in Levels 1 and 2 Fair Value Measurements

The determination to classify a financial instrument within Level 1 or Level 2 is based upon the availability of quoted prices for identical or similar assets and liabilities in active markets. Depending upon the information readily observable in the market, and/or the use of identical or similar quoted prices, which are significant to the overall valuation, the classification of any individual financial instrument may differ from one measurement date to the next. To qualify as a transfer, the asset or liability must have existed in the previous reporting period and moved into a different level during the current period. In the event that there is a movement between the classification of an instrument as Level 1 or 2, the transfer would be reflected in a table as “Transfers into or out of Level 1 and Level 2”. During the years ended December 31, 2018 and 2017, there were no transfers between Level 1 and Level 2 of the fair value hierarchy.

Changes in Level 3 Fair Value Measurements

The tables below illustrate a rollforward of the amounts included in our consolidated balance sheets for derivative financial instruments that we have classified within Level 3. Since financial instruments classified as Level 3 typically include a combination of observable components (that is, components that are actively quoted and can be validated to external sources) and unobservable components, the gains and losses in the table below may include changes in fair value due in part to observable market factors, or changes to our assumptions on the unobservable components. Depending upon the information readily observable in the market, and/or the use of unobservable inputs, which are significant to the overall valuation, the classification of any individual financial instrument may differ from one measurement date to the next. The significant unobservable inputs used in determining fair value include adjustments by other market-based or independently sourced market data such as historical commodity volatilities, crude oil future yield curves, and/or counterparty specific considerations. In the event that there is a movement to/from the classification of an instrument as Level 3, we would reflect such items in the table below within the “Transfers into/out of Level 3” captions.

We manage our overall risk at the portfolio level and in the execution of our strategy, we may use a combination of financial instruments, which may be classified within any level. Since Level 1 and Level 2 risk management instruments are not included in the rollforward below, the gains or losses in the table do not reflect the effect of our total risk management activities.



	Commodity Derivative Instruments
	Current Assets			Long-Term Assets			Current Liabilities			Long-Term Liabilities
	(millions)
Year ended December 31, 2018 (a):
Beginning balance	$	3		$	1		$	(13	)	$	(1	)
Net unrealized gains (losses) included in earnings (b)	14			1			(6		)	(1		)
Settlements	(3		)	—			19			—
Ending balance	$	14		$	2		$	—		$	(2	)
Net unrealized gains (losses) on derivatives still held included in earnings (b)	$	14		$	1		$	—		$	(1	)
Year ended December 31, 2017 (a):
Beginning balance	$	9		$	5		$	(23	)	$	—
Net unrealized gains (losses) included in earnings (b)	14			1			(44		)	(3		)
Transfers out of Level 3 (c)	—			—			—			2
Settlements	(13		)	—			36			—
CME Rule 814 adjustment	(7		)	(5		)	18			—
Ending balance	$	3		$	1		$	(13	)	$	(1	)
Net unrealized gains (losses) on derivatives still held included in earnings (b)	$	3		$	(4	)	$	(13	)	$	(1	)


(a)	There were no purchases, issuances or sales of derivatives or transfers into Level 3 for the three and years ended December 31, 2018 and 2017.


(b)	Represents the amount of unrealized gains or losses for the period, included in trading and marketing gains (losses), net.


(c)	Amounts transferred out of Level 3 are reflected at fair value at the end of the period.

Quantitative Information and Fair Value Sensitivities Related to Level 3 Unobservable Inputs

We utilize the market approach to measure the fair value of our commodity contracts. The significant unobservable inputs used in this approach to fair value are longer dated price quotes. Our sensitivity to these longer dated forward curve prices are presented in the table below. Significant changes in any of those inputs in isolation would result in significantly different fair value measurements, depending on our short or long position in contracts.



	December 31, 2018
Product Group	Fair Value			Forward Curve Range
	(millions)
Assets
NGLs	$	14		$0.31-$0.96	Per gallon
Natural gas	$	2		$2.01-$2.56	Per MMBtu
Liabilities
Natural gas	$	(2	)	$2.46-$2.88	Per MMBtu

Estimated Fair Value of Financial Instruments

Valuation of a contract’s fair value is validated by an internal group independent of the marketing group. While common industry practices are used to develop valuation techniques, changes in pricing methodologies or the underlying assumptions could result in significantly different fair values and income recognition. When available, quoted market prices or prices obtained through external sources are used to determine a contract’s fair value. For contracts with a delivery location or duration for which quoted market prices are not available, fair value is determined based on pricing models developed primarily from historical and expected relationships with quoted market prices.

The fair value of our interest rate swaps, if any, and commodity non-trading derivatives is based on prices supported by quoted market prices and other external sources and prices based on models and other valuation methods. The “prices supported by quoted market prices and other external sources” category includes our interest rate swaps, if any, our NGL and crude oil swaps and our NYMEX positions in natural gas. In addition, this category includes our forward positions in natural gas for which our forward price curves are obtained from a third party pricing service and then validated through an internal process which includes the use of independent broker quotes. This category also includes our forward positions in NGLs at points for which OTC broker quotes for similar assets or liabilities are available for the full term of the instrument. This category also includes “strip” transactions whose pricing inputs are directly or indirectly observable from external sources and then modeled to daily or monthly prices as appropriate. The “prices based on models and other valuation methods” category includes the value of transactions for which inputs to the fair value of the instrument are unobservable in the marketplace and are considered significant to the overall fair value of the instrument. The fair value of these instruments may be based upon an internally developed price curve, which was constructed as a result of the long dated nature of the transaction or the illiquidity of the specific market point.

We have determined fair value amounts using available market information and appropriate valuation methodologies. However, considerable judgment is required in interpreting market data to develop the estimates of fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts that we could realize in a current market exchange. The use of different market assumptions and/or estimation methods may have a material effect on the estimated fair value amounts.

The fair value of accounts receivable and accounts payable are not materially different from their carrying amounts because of the short-term nature of these instruments or the stated rates approximating market rates. Derivative instruments are carried at fair value.

We determine the fair value of our fixed-rate senior notes and junior subordinated notes based on quotes obtained from bond dealers. The fair value of borrowings under the Credit Agreement and the Securitization Facility are based on carrying value, which approximates fair value as their interest rates are based on prevailing market interest rates. We classify the fair values of our outstanding debt balances within Level 2 of the valuation hierarchy. As of December 31, 2018 and December 31, 2017, the carrying value and fair value of our total debt, including current maturities, were as follows:



		December 31, 2018				December 31, 2017
		Carrying Value (a)		Fair Value		Carrying Value (a)		Fair Value
	(millions)

Total debt		$	5,337	$	5,170	$	4,736	$	4,885

(a) Excludes unamortized issuance costs.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Debt

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Debt



	December 31, 2018			December 31, 2017
	(millions)
Senior notes:
Issued February 2009, interest at 9.750% payable semiannually, due March 2019 (a)	$	—		$	450
Issued March 2014, interest at 2.700% payable semi-annually, due April 2019	325			325
Issued March 2010, interest at 5.350% payable semiannually, due March 2020 (a)	600			600
Issued September 2011, interest at 4.750% payable semiannually, due September 2021	500			500
Issued March 2012, interest at 4.950% payable semi-annually, due April 2022	350			350
Issued March 2013, interest at 3.875% payable semi-annually, due March 2023	500			500
Issued July 2018, interest at 5.375% payable semi-annually, due July 2025	500			—
Issued August 2000, interest at 8.125% payable semi-annually, due August 2030 (a)	300			300
Issued October 2006, interest at 6.450% payable semi-annually, due November 2036	300			300
Issued September 2007, interest at 6.750% payable semi-annually, due September 2037	450			450
Issued March 2014, interest at 5.600% payable semi-annually, due April 2044	400			400
Junior subordinated notes:
Issued May 2013, interest at 5.850% payable semi-annually, due May 2043	550			550
Credit agreement:
Revolving credit facility, weighted-average variable interest rate of 3.901%, as of December 31, 2018, due December 2022	351			—
Accounts receivable securitization facility:
Accounts receivable securitization facility, weighted-average variable interest rate of 3.303% as of December 31, 2018, due August 2019	200			—
Fair value adjustments related to interest rate swap fair value hedges (a)	21			23
Unamortized issuance costs	(30		)	(29		)
Unamortized discount	(10		)	(12		)
Total debt	5,307			4,707
Current debt	525			—
Total long-term debt	$	4,782		$	4,707

(a) The swaps associated with this debt were previously terminated. The remaining long-term fair value of approximately

$21 million related to the swaps is being amortized as a reduction to interest expense through 2020 and 2030, the original maturity dates of the debt.

Accounts Receivable Securitization Facility

In August 2018, we entered into our Securitization Facility that provides up to $200 million of borrowing capacity through August 2019 at LIBOR market index rates plus a margin. Under this Securitization Facility, certain of the Partnership’s wholly owned subsidiaries sell or contribute receivables to another of the Partnership’s consolidated subsidiaries, DCP Receivables LLC (“DCP Receivables”), a bankruptcy-remote special purpose entity created for the sole purpose of this Securitization Facility.

DCP Receivables’ sole activity consists of purchasing receivables from the Partnership’s wholly owned subsidiaries that participate in the Securitization Facility and providing these receivables as collateral for DCP Receivables’ borrowings under the Securitization Facility. DCP Receivables is a separate legal entity and the accounts receivable of DCP Receivables, up to the amount of the outstanding debt under the Securitization Facility, are not available to satisfy the claims of creditors of the Partnership, its subsidiaries selling receivables under the Securitization Facility, or their affiliates. Any excess receivables are eligible to satisfy the claims of creditors of the Partnership, its subsidiaries selling receivables under the Securitization Facility, or their affiliates. The amount available for borrowing is based on the availability of eligible receivables and other customary factors and conditions. As of December 31, 2018, DCP Receivables had $831 million of our accounts receivable under its Securitization Facility. Borrowings under the Securitization Facility are included in “Current debt” on the consolidated balance sheet.

Senior Notes Redemption

In August 2018, we redeemed our outstanding $450 million 9.750% Senior Notes due March 2019, totaling $468 million in aggregate principal and make-whole payments, at a price of 104.008% plus accrued interest through the redemption date. The redemption resulted in a $19 million loss, which is reflected as loss from financing activities on the consolidated statements of operations.

Senior Notes Issuance

On July 17, 2018, we issued $500 million of 5.375% Senior Notes due July 2025, unless redeemed prior to maturity. We received proceeds of $495 million, net of underwriters’ fees, related expenses and unamortized discounts which we used to redeem our $450 million 9.750% Senior Notes due March 2019. Interest on the notes will be paid semi-annually in arrears on January 15 and July 15 of each year, commencing January 15, 2019.

Credit Agreement

We are a party to a $1.4 billion unsecured revolving Credit Agreement (the "Credit Agreement") which matures on December 6, 2022. The Credit Agreement also grants us the option to increase the revolving loan commitment by an aggregate principal amount of up to $500 million, subject to requisite lender approval. The Credit Agreement may be extended for up to two additional one-year periods subject to requisite lender approval. Loans under the Credit Agreement may be used for working capital and other general partnership purposes including acquisitions.

The Credit Agreement allows for unrestricted cash and cash equivalents to be netted against consolidated indebtedness for purposes of calculating the Partnership’s Consolidated Leverage Ratio (as defined in the Credit Agreement). Additionally, under the Credit Agreement, the Consolidated Leverage Ratio of the Partnership as of the end of any fiscal quarter shall not exceed 5.00 to 1.0 for each fiscal quarter ending after September 30, 2018; provided that, if there is a Qualified Acquisition (as defined in the Credit Agreement) during any fiscal quarter ending September 30, 2018 or thereafter, the maximum Consolidated Leverage Ratio shall not exceed 5.50 to 1.0 at the end of the three consecutive fiscal quarters, including the fiscal quarter in which the Qualified Acquisition occurs.

Our cost of borrowing under the Credit Agreement is determined by a ratings-based pricing grid. Indebtedness under the Credit Agreement bears interest at either: (1) LIBOR, plus an applicable margin of 1.45% based on our current credit rating; or (2) (a) the base rate which shall be the higher of the prime rate, the Federal Funds rate plus 0.50% or the LIBOR Market Index rate plus 1%, plus (b) an applicable margin of 0.45% based on our current credit rating. The Credit Agreement incurs an annual facility fee of 0.30% based on our current credit rating. This fee is paid on drawn and undrawn portions of the $1.4 billion revolving credit facility.

As of December 31, 2018, we had unused borrowing capacity of $1,036 million, net of $13 million of letters of credit, under the Credit Agreement. Our borrowing capacity may be limited by financial covenants set forth in the Credit Agreement. The financial covenants set forth in the Credit Agreement limit the Partnership's ability to incur incremental debt by the unused borrowing capacity of $1,036 million as of December 31, 2018. Except in the case of a default, amounts borrowed under our Credit Agreement will not become due prior to the December 6, 2022 maturity date.

Senior Notes and Junior Subordinated Notes

Our senior notes and junior subordinated notes, collectively referred to as our debt securities, mature and become payable on their respective due dates, and are not subject to any sinking fund or mandatory redemption provisions. The senior notes are senior unsecured obligations that are guaranteed by the Partnership and rank equally in a right of payment with our other senior unsecured indebtedness, including indebtedness under our Credit Agreement, and the junior subordinated notes are unsecured and rank subordinate in right of payment to all of our existing and future senior indebtedness. The debt securities include an optional redemption whereby we may elect to redeem the notes, in whole or in part from time-to-time for a premium. Additionally, we may defer the payment of all or part of the interest on the junior subordinated notes for one or more periods up to five consecutive years. The underwriters’ fees and related expenses are recorded in our consolidated balance sheets within the carrying amount of long-term debt and will be amortized over the term of the notes.

The maturities of our debt as of December 31, 2018 are as follows:



	Debt Maturities
	(millions)
2019	$	525
2020	600
2021	500
2022	701
2023	500
Thereafter	2,500
Total debt	$	5,326

Risk Management and Hedging Activities

12 Months Ended

Dec. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Risk Management and Hedging Activities

Our operations expose us to a variety of risks including but not limited to changes in the prices of commodities that we buy or sell, changes in interest rates, and the creditworthiness of each of our counterparties. We manage certain of these exposures with either physical or financial transactions. We have established a comprehensive risk management policy and a risk management committee, or the Risk Management Committee, to monitor and manage market risks associated with commodity prices and counterparty credit. The Risk Management Committee is composed of senior executives who receive regular briefings on positions and exposures, credit exposures and overall risk management in the context of market activities. The Risk Management Committee is responsible for the overall management of credit risk and commodity price risk, including monitoring exposure limits. The following describes each of the risks that we manage.

Commodity Price Risk

Our portfolio of commodity derivative activity is primarily accounted for using the mark-to-market method of accounting; however, depending upon our risk profile and objectives, in certain limited cases, we may execute transactions that qualify for the hedge method of accounting. The risks, strategies and instruments used to mitigate such risks, as well as the method of accounting are discussed and summarized below.

Natural Gas Asset Based Trading and Marketing

Our natural gas storage and pipeline assets are exposed to certain risks including changes in commodity prices. We manage commodity price risk related to our natural gas storage and pipeline assets through our commodity derivative program. The commercial activities related to our natural gas storage and pipeline assets primarily consist of the purchase and sale of gas and associated time spreads and basis spreads.

A time spread transaction is executed by establishing a long gas position at one point in time and establishing an equal short gas position at a different point in time. Time spread transactions allow us to lock in a margin supported by the injection, withdrawal, and storage capacity of our natural gas storage assets. We may execute basis spread transactions to mitigate the risk of sale and purchase price differentials across our system. A basis spread transaction allows us to lock in a margin on our physical purchases and sales of gas, including injections and withdrawals from storage. We typically use swaps to execute these transactions, which are not designated as hedging instruments and are recorded at fair value with changes in fair value recorded in the current period consolidated statements of operations. While gas held in our storage locations is recorded at the lower of average cost or market, the derivative instruments that are used to manage our storage facilities are recorded at fair value and any changes in fair value are currently recorded in our consolidated statements of operations. Even though we may have economically hedged our exposure and locked in a future margin, the use of lower-of-cost-or-market accounting for our physical inventory and the use of mark-to-market accounting for our derivative instruments may subject our earnings to market volatility.

Commodity Cash Flow Hedges

In order for our natural gas storage facility to remain operational, a minimum level of base gas must be maintained in each storage cavern, which is capitalized on our consolidated balance sheets as a component of property, plant and equipment, net. During construction or expansion of our storage caverns, we may execute a series of derivative financial instruments to mitigate a portion of the risk associated with the forecasted purchase of natural gas when we bring the storage caverns into operation. These derivative financial instruments may be designated as cash flow hedges. While the cash paid upon settlement of these hedges economically fixes the cash required to purchase base gas, the deferred losses or gains would remain in accumulated other comprehensive income, or AOCI, until the cavern is emptied and the base gas is sold. The balance in AOCI of our previously settled base gas cash flow hedges was in a loss position of $6 million as of December 31, 2018.

Commodity Cash Flow Protection Activities

We are exposed to the impact of market fluctuations in the prices of natural gas, NGLs and condensate as a result of our gathering, processing, sales and storage activities. For gathering, processing and storage services, we may receive cash or commodities as payment for these services, depending on the contract type. We may enter into derivative financial instruments to mitigate a portion of the risk of weakening natural gas, NGL and condensate prices associated with our gathering, processing and sales activities, thereby stabilizing our cash flows. As of December 31, 2018 our derivative financial instruments used to mitigate a portion of the risk of weakening natural gas, NGL and condensate prices extend through the first quarter of 2020. The commodity derivative instruments used for our hedging programs are a combination of direct NGL product, crude oil and natural gas hedges. Crude oil and NGL transactions are primarily accomplished through the use of forward contracts that effectively exchange floating price risk for a fixed price. The type of instrument used to mitigate a portion of the risk may vary depending on our risk management objectives. These transactions are not designated as hedging instruments for accounting purposes and the change in fair value is reflected in the current period within our consolidated statements of operations as trading and marketing gains and (losses), net.

NGL Proprietary Trading

Our NGL proprietary trading activity includes trading energy related products and services. We undertake these activities through the use of fixed forward sales and purchases, basis and spread trades, storage opportunities, put/call options, term contracts and spot market trading. These energy trading operations are exposed to market variables and commodity price risk with respect to these products and services, and these operations may enter into physical contracts and financial instruments with the objective of realizing a positive margin from the purchase and sale of commodity-based instruments. These physical and financial instruments are not designated as hedging instruments and are recorded at fair value with changes in fair value recorded in the current period consolidated statements of operations.

We employ established risk limits, policies and procedures to manage risks associated with our natural gas asset based trading and marketing and NGL proprietary trading.

Credit Risk

Our principal customers range from large, natural gas marketers to industrial end-users for our natural gas products and services, as well as large multi-national petrochemical and refining companies, to small regional propane distributors for our NGL products and services. Substantially all of our natural gas and NGL sales are made at market-based prices. This concentration of credit risk may affect our overall credit risk, in that these customers may be similarly affected by changes in economic, regulatory or other factors. Where exposed to credit risk, we analyze the counterparties’ financial condition prior to entering into an agreement, establish credit limits and monitor the appropriateness of these limits on an ongoing basis. We may use various master agreements that include language giving us the right to request collateral to mitigate credit exposure. The collateral language provides for a counterparty to post cash or letters of credit for exposure in excess of the established threshold. The threshold amount represents an open credit limit, determined in accordance with our credit policy. The collateral language also provides that the inability to post collateral is sufficient cause to terminate a contract and liquidate all positions. In addition, our master agreements and our standard gas and NGL sales contracts contain adequate assurance provisions, which allow us to suspend deliveries and cancel agreements, or continue deliveries to the buyer after the buyer provides acceptable security for payment.

Contingent Credit Features

Each of the above risks is managed through the execution of individual contracts with a variety of counterparties. Certain of our derivative contracts may contain credit-risk related contingent provisions that may require us to take certain actions in certain circumstances.

We have International Swaps and Derivatives Association, or ISDA, contracts which are standardized master legal arrangements that establish key terms and conditions which govern certain derivative transactions. These ISDA contracts contain standard credit-risk related contingent provisions. Some of the provisions we are subject to are outlined below.


•	If we were to have an effective event of default under our Credit Agreement that occurs and is continuing, our ISDA counterparties may have the right to request early termination and net settlement of any outstanding derivative liability positions.


•	Our ISDA counterparties generally have collateral thresholds of zero, requiring us to fully collateralize any commodity contracts in a net liability position, when our credit rating is below investment grade.

•

Additionally, in some cases, our ISDA contracts contain cross-default provisions that could constitute a credit-risk related contingent feature. These provisions apply if we default in making timely payments under other credit arrangements and the amount of the default is above certain predefined thresholds, which are significantly high and are generally consistent with the terms of our Credit Agreement. As of December 31, 2018, we were not a party to any agreements that would trigger the cross-default provisions.

Our commodity derivative contracts that are not governed by ISDA contracts do not have any credit-risk related contingent features. Depending upon the movement of commodity prices and interest rates, each of our individual contracts with counterparties to our commodity derivative instruments or interest rate swap instruments are in either a net asset or net liability position. As of December 31, 2018, we did not have any individual commodity derivative contracts that contain credit-risk related contingent features that were in a net liability position. If we were required to net settle our position with an individual counterparty, due to a credit-risk related event, our ISDA contracts may permit us to net all outstanding contracts with that counterparty, whether in a net asset or net liability position, as well as any cash collateral already posted. As of December 31, 2018, we have not been required to post additional collateral.

Collateral

As of December 31, 2018, we had cash deposits of $34 million, included in collateral cash deposits in our consolidated balance sheets. Additionally, as of December 31, 2018, we held cash of $13 million, included in other current liabilities in our consolidated balance sheet, related to cash postings by third parties and letters of credit of $105 million from counterparties to secure their future performance under financial or physical contracts. Collateral amounts held or posted may be fixed or may vary, depending on the value of the underlying contracts, and could cover normal purchases and sales, services, trading and hedging contracts. In many cases, we and our counterparties have publicly disclosed credit ratings, which may impact the amounts of collateral requirements.

Physical forward contracts and financial derivatives are generally cash settled at the expiration of the contract term. These transactions are generally subject to specific credit provisions within the contracts that would allow the seller, at its discretion, to suspend deliveries, cancel agreements or continue deliveries to the buyer after the buyer provides security for payment satisfactory to the seller.

Offsetting

Certain of our derivative instruments are subject to a master netting or similar arrangement, whereby we may elect to settle multiple positions with an individual counterparty through a single net payment. Each of our individual derivative instruments are presented on a gross basis on the consolidated balance sheets, regardless of our ability to net settle our positions. Instruments that are governed by agreements that include net settle provisions allow final settlement, when presented with a termination event, of outstanding amounts by extinguishing the mutual debts owed between the parties in exchange for a net amount due. We have trade receivables and payables associated with derivative instruments, subject to master netting or similar agreements, which are not included in the table below. The following summarizes the gross and net amounts of our derivative instruments:



	December 31, 2018								December 31, 2017
	Gross Amounts of Assets and (Liabilities) Presented in the Balance Sheet			Amounts Not Offset in the Balance Sheet - Financial Instruments		Net Amount			Gross Amounts of Assets and (Liabilities) Presented in the Balance Sheet			Amounts Not Offset in the Balance Sheet - Financial Instruments		Net Amount
	(millions)
Assets:
Commodity derivatives	$	116		$	—	$	116		$	33		$	—	$	33
Liabilities:
Commodity derivatives	$	(99	)	$	—	$	(99	)	$	(91	)	$	—	$	(91	)

Summarized Derivative Information

The fair value of our derivative instruments that are marked-to-market each period, as well as the location of each within our consolidated balance sheets, by major category, is summarized below. We have no derivative instruments that are designated as hedging instruments for accounting purposes as of December 31, 2018 and December 31, 2017.



Balance Sheet Line Item	December 31, 2018		December 31, 2017		Balance Sheet Line Item	December 31, 2018			December 31, 2017
	(millions)					(millions)
Derivative Assets Not Designated as Hedging Instruments:					Derivative Liabilities Not Designated as Hedging Instruments:
Commodity derivatives:					Commodity derivatives:
Unrealized gains on derivative instruments — current	$	108	$	30	Unrealized losses on derivative instruments — current	$	(91	)	$	(76	)
Unrealized gains on derivative instruments — long-term	8		3		Unrealized losses on derivative instruments — long-term	(8		)	(15		)
Total	$	116	$	33	Total	$	(99	)	$	(91	)

The following summarizes the balance and activity within AOCI relative to our interest rate, commodity and foreign currency cash flow hedges as of and for the year ended December 31, 2018:



	Interest Rate Cash Flow Hedges			Commodity Cash Flow Hedges			Foreign Currency Cash Flow Hedges (a)		Total
	(millions)
Net deferred (losses) gains in AOCI (beginning balance)	$	(4	)	$	(6	)	$	1	$	(9	)
Losses reclassified from AOCI to earnings — effective portion	1			—			—		1
Net deferred (losses) gains in AOCI (ending balance)	$	(3	)	$	(6	)	$	1	$	(8	)
Deferred losses in AOCI expected to be reclassified into earnings over the next 12 months	$	(1	)	$	—		$	—	$	(1	)

(a)Relates to Discovery Producer Services LLC ("Discovery"), an unconsolidated affiliate.

The following summarizes the balance and activity within AOCI relative to our interest rate, commodity and foreign currency cash flow hedges as of and for the year ended December 31, 2017:



	Interest Rate Cash Flow Hedges			Commodity Cash Flow Hedges			Foreign Currency Cash Flow Hedges (a)		Total
	(millions)
Net deferred (losses) gains in AOCI (beginning balance)	$	(3	)	$	(6	)	$	1	$	(8	)
Losses reclassified from AOCI to earnings — effective portion	1			—			—		1
Deficit purchase price under carrying value	(2		)	—			—		(2		)
Net deferred (losses) gains in AOCI (ending balance)	$	(4	)	$	(6	)	$	1	$	(9	)


(a)	Relates to Discovery, an unconsolidated affiliate.

For the years ended December 31, 2018 and 2017, no derivative losses attributable to the ineffective portion or to amounts excluded from effectiveness testing were recognized in trading and marketing gains or losses, net or interest expense in our consolidated statements of operations. For the years ended December 31, 2018 and 2017, no derivative losses were reclassified from AOCI to trading and marketing gains or losses, net or interest expense as a result of the discontinuance of cash flow hedges related to certain forecasted transactions that are not probable of occurring.

Changes in the value of derivative instruments, for which the hedge method of accounting has not been elected from one period to the next, are recorded in the consolidated statements of operations. The following summarizes these amounts and the location within the consolidated statements of operations that such amounts are reflected:



Commodity Derivatives: Statements of Operations Line Item		Year Ended December 31,
		2018			2017			2016
	(millions)
Realized (losses) gains		$	(149	)	$	(12	)	$	116
Unrealized gains (losses)		108			(28		)	(139		)
Trading and marketing losses, net		$	(41	)	$	(40	)	$	(23	)

We do not have any derivative financial instruments that qualify as a hedge of a net investment.

The following tables represent, by commodity type, our net long or short positions that are expected to partially or entirely settle in each respective year. To the extent that we have long dated derivative positions that span multiple calendar years, the contract will appear in more than one line item in the tables below.



	December 31, 2018
	Crude Oil		Natural Gas		Natural Gas Liquids		Natural Gas Basis Swaps
Year of Expiration	Net Short Position (Bbls)		Net Short Position (MMBtu)		Net Short Position (Bbls)		Net (Short) Long Position (MMBtu)
2019	(1,619,000	)	(40,291,250	)	(36,312,499	)	(2,165,000	)
2020	(204,000	)	—		(13,862,378	)	3,660,000
2021	—		—		(5,755,322	)	(3,650,000	)

	December 31, 2017
	Crude Oil		Natural Gas		Natural Gas Liquids		Natural Gas Basis Swaps
Year of Expiration	Net Short Position (Bbls)		Net Short Position (MMBtu)		Net (Short) Long Position (Bbls)		Net Long Position (MMBtu)
2018	(2,701,000	)	(35,977,400	)	(19,656,392	)	3,202,500
2019	(631,000	)	—		(2,357,156	)	7,177,500
2020	(50,000	)	—		238,548		3,660,000

Partnership Equity and Distributions

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Partnership Equity and Distributions

Preferred Units — In October 2018 , we issued 4,400,000 of our Series C Preferred Units representing limited partnership interests (including a partial exercise of the underwriters’ option to purchase additional Series C Preferred Units) at a price of $25 per unit. We used the net proceeds of $106 million from the issuance of the Series C Preferred Units for general partnership purposes including funding capital expenditures and the repayment of outstanding indebtedness under the Credit Agreement.

Distributions of the Series C Preferred Units are payable out of available cash, accrue and are cumulative from the date of original issuance of the Series C Preferred Units and are payable quarterly in arrears on January 15th, April 15th, July 15th and October 15th of each year to holders of record as of the close of business on the first business day of the month in which the distribution will be made. The initial distribution rate will be 7.950% per year of the $25 liquidation preference per unit (equal to $1.9875 per unit). On and after October 15, 2023, distributions will accumulate at a percentage of the $25 liquidation preference equal to an annual floating rate of the three-month LIBOR plus a spread of 4.882%. The Series C Preferred Units rank senior to our common units with respect to distribution rights and rights upon liquidation.

In addition, during the year ended December 31, 2018, we issued 6,450,000 of our Series B Preferred Units for net proceeds of $155 million, net of offering costs. During the year ended December 31, 2017, we issued $487 million of our Series A Preferred Units, net of offering costs.

Distributions of the Preferred Units are payable out of available cash, accrue and are cumulative from the date of original issuance of the Preferred Units.


•	Distributions on the Series A Preferred Units are payable semiannually in arrears on June 15th and December 15th of each year.


•	Distributions on the Series B Preferred Units are payable quarterly in arrears on the 15th day of March, June, September and December of each year to holders of record as of the close of business on the first business day of the month in which the distribution will be made.


•	Distributions on the Series C Preferred Units are payable quarterly in arrears on the 15th day of January, April, July and October of each year to holders of record as of the close of business on the first business day of the month in which the distribution will be made.

The Preferred Units rank senior to our common units with respect to distribution rights and rights upon liquidation. Holders of the Preferred Units have no voting rights except for certain limited protective voting rights set forth in our Partnership Agreement.

Common Units — During the years ended December 31, 2018 and 2017, we issued no common units pursuant to our at-the-market program. As of December 31, 2018, $750 million of common units remained available for sale pursuant to our at-the-market program.

Definition of Available Cash — Our Partnership Agreement requires that, within 45 days after the end of each quarter, we distribute all of our Available Cash, as defined in the Partnership Agreement, to unitholders of record on the applicable record date, as determined by our general partner. Available Cash, for any quarter, consists of all cash and cash equivalents on hand at the end of that quarter:


•	less the amount of cash reserves established by our general partner to:


•	provide for the proper conduct of our business, including reserves for future capital expenditures and anticipated credit needs;


•	comply with applicable law or any debt instrument or other agreement or obligation;


•	provide funds to make payments on the Preferred Units; or


•	provide funds for distributions to our common unitholders and to our general partner for any one or more of the next four quarters.


•	plus, if our general partner so determines, all or a portion of cash and cash equivalents on hand on the date of determination of Available Cash for the quarter.

General Partner Interest and Incentive Distribution Rights - The general partner is entitled to a percentage of all quarterly distributions equal to its general partner interest of approximately 2% and limited partner interest of approximately 36% as of December 31, 2018. The general partner has the right, but not the obligation, to contribute a proportionate amount of capital to us to maintain its current general partner or limited partner interest.

The incentive distribution rights held by the general partner entitle it to receive an increasing share of Available Cash when pre-defined distribution targets are achieved. Currently, our distribution to our general partner related to its incentive distribution rights is at the highest level. The general partner’s incentive distribution rights were not reduced as a result of our common unit and preferred unit issuances, and will not be reduced if we issue additional units in the future and the general partner does not contribute a proportionate amount of capital to us to maintain its current general partner interest. Please read the Distributions of Available Cash sections below for more details about the distribution targets and their impact on the general partner’s incentive distribution rights.

As part of the Transaction, Phillips 66 and Enbridge agreed, if required, to provide a reduction to incentive distributions payable to our General Partner under our Partnership Agreement of up to $100 million annually through 2019 to target an approximate 1.0 times distribution coverage ratio. Under the terms of our amended Partnership Agreement, the amount of incentive distributions paid to our General Partner will be evaluated by our General Partner on both a quarterly and annual basis and may be reduced each quarter by an amount determined by our General Partner (the “IDR giveback”). If no determination is made by our General Partner, the quarterly IDR giveback will be $20 million. The IDR giveback, of up to $100 million annually, will be subject to a true-up at the end of the year by taking our total distributable cash flow (as adjusted under our amended Partnership Agreement) less the total annual distribution payable to our unitholders, adjusted to target an approximate 1.0 times coverage ratio. During the year ended December 31, 2018 and in conjunction with the quarterly distribution, the Partnership distributed $40 million of incentive distribution rights ("IDR") givebacks to the IDR holders that were previously withheld under the amended Partnership Agreement during the year ended December 31, 2017, in accordance with the Third Amendment to the Partnership Agreement.

Distributions of Available Cash - Our Partnership Agreement, after adjustment for the general partner’s relative ownership level, requires that we make distributions of Available Cash from operating surplus for any quarter in the following manner:


•	first, to all unitholders and the general partner, in accordance with their pro rata interest, until each unitholder receives a total of $0.4025 per unit for that quarter;


•	second, 13% to the general partner, plus the general partner’s pro rata interest, and the remainder to all unitholders pro rata until each unitholder receives a total of $0.4375 per unit for that quarter;


•	third, 23% to the general partner, plus the general partner’s pro rata interest, and the remainder to all unitholders pro rata until each unitholder receives a total of $0.525 per unit for that quarter; and


•	thereafter, 48% to the general partner, plus the general partner’s pro rata interest, and the remainder to all unitholders.

Distributions — The following table presents our cash distributions paid in 2018, 2017 and 2016:



Payment Date	Per Unit Distribution		Total Cash Distribution
			(millions)
Distributions to common unitholders
November 14, 2018	$	0.7800	$	155
August 14, 2018	$	0.7800	$	154
May 15, 2018	$	0.7800	$	155
February 14, 2018	$	0.7800	$	194
November 14, 2017	$	0.7800	$	155
August 14, 2017	$	0.7800	$	134
May 15, 2017	$	0.7800	$	135
February 14, 2017	$	0.7800	$	121
November 14, 2016	$	0.7800	$	120
August 12, 2016	$	0.7800	$	121
May 13, 2016	$	0.7800	$	121
February 12, 2016	$	0.7800	$	121

Distributions to Series A Preferred unitholders
December 17, 2018	$	36.8750	$	18
June 15, 2018	$	41.9965	$	21

Distributions to Series B Preferred unitholders
December 17, 2018	$	0.4922	$	3
September 17, 2018	$	0.6781	$	4

Equity-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Equity-Based Compensation

15. Equity-Based Compensation

On April 28, 2016, the unitholders of the Partnership approved the 2016 Long-Term Incentive Plan (the “2016 LTIP” and, together with the 2012 LTIP, the “LTIP”). The 2016 plan authorizes up to 900,000 common units to be available for issuance under awards to employees, officers, and non-employee directors of the General Partner and its affiliates. Awards under the 2016 LTIP may include unit options, phantom units, restricted units, distribution equivalent rights, unit bonuses, common unit awards, and performance awards. The 2016 LTIP will expire on the earlier of the date it is terminated by the board of directors of the General Partner or the date that all common units available under the plan have been paid or issued.

On February 15, 2012, the board of directors of our General Partner adopted the 2012 LTIP (the "2012 LTIP") for employees, consultants and directors of our General Partner and its affiliates who perform services for us. The 2012 LTIP provided for the grant of phantom units and DERs. The 2012 LTIP phantom units consist of a notional unit based on the value of common units or shares of Phillips 66 and Enbridge. The LTIPs are administered by the General Partner’s board of directors. All awards under the LTIPs are subject to cliff vesting.

Since we have the intent and ability to settle certain awards within our control in units, we classify them as equity awards based on their fair value. The fair value of our equity awards is determined based on the closing price of our common units on the grant date. Compensation expense on equity awards is recognized ratably over each vesting period. We account for other awards which are subject to settlement in cash, including DERs, as liability awards. Compensation expense on these awards is recognized ratably over each vesting period, and will be re-measured each reporting period for all awards outstanding until the units are vested. The fair value of all liability awards is determined based on the closing price of our common units at each measurement date.

Under DCP Midstream, LLC's Long-Term Incentive Plan ("DCP Midstream LTIP"), awards may be granted to key employees. The DCP Midstream LTIP provides for the grant of Strategic Performance Units ("SPUs") and Phantom Units. The SPUs and Phantom Units consist of a notional unit based on the fair market value of a common unit of the Partnership. Prior to 2018, the SPUs and Phantom Units consisted of a notional unit based on the weighted average value of common shares of Phillips 66 and Enbridge as of the grant date.

Liability classified equity-based compensation expense was $11 million, $23 million and $18 million for the years ended December 31, 2018, 2017 and 2016, respectively.

The following table presents the fair value of unvested unit-based awards related to the strategic performance units and phantom units:



	Vesting Period (years)	Unrecognized Compensation Expense at December 31, 2018 (millions)		Estimated Forfeiture Rate	Weighted-Average Remaining Vesting (years)
DCP Midstream LTIP:
SPUs	3	$	4	0%-11%	2
Phantom Units	1-3	$	4	0%-11%	2

Strategic Performance Units - The number of SPUs that will ultimately vest range in value of up to 200% of the outstanding SPUs, depending on the achievement of specified performance targets over a three year period. The final performance payout is determined by the compensation committee of our General Partner. The DERs are paid in cash at the end of the performance period. The following table presents information related to SPUs:



	Units		Grant Date Weighted-Average Price Per Unit		Measurement Date Weighted-Average Price Per Unit
Outstanding at January 1, 2016	208,459		$	48.46
Granted	131,610		$	45.31
Forfeited	(8,463	)	$	46.27
Vested (a)	(98,295	)	$	54.05
Outstanding at December 31, 2016	233,311		$	44.41
Granted	98,628		$	76.38
Forfeited	(18,577	)	$	50.31
Vested (b)	(98,627	)	$	58.80
Outstanding at December 31, 2017	214,735		$	51.98
Granted	168,160		$	36.23
Forfeited	(10,933	)	$	47.79
Vested (c)	(120,643	)	$	48.41
Outstanding at December 31, 2018	251,319		$	43.33	$	34.30
Expected to vest	231,936		$	43.54	$	34.53

(a) The 2014 grants vested at 130%.

(b) The 2015 grants vested at 180%.

The estimate of SPUs that are expected to vest is based on highly subjective assumptions that could change over time, including the expected forfeiture rate and achievement of performance targets.

The following table presents the fair value of units vested and the unit-based liabilities paid for unit-based awards related to the strategic performance units:



	Units	Fair Value of Units Vested		Unit-Based Liabilities Paid
		(millions)
Vested or paid in cash in 2016	98,295	$	7	$	4
Vested or paid in cash in 2017	98,627	$	11	$	7
Vested or paid in cash in 2018	120,643	$	9	$	11

Phantom Units - The DERs are paid quarterly in arrears. The following table presents information related to Phantom Units:



	Units		Grant Date Weighted-Average Price Per Unit		Measurement Date Weighted-Average Price Per Unit
Outstanding at January 1, 2016	204,368		$	49.85
Granted	132,870		$	45.33
Forfeited	(3,240	)	$	48.62
Vested	(126,681	)	$	50.13
Outstanding at December 31, 2016	207,317		$	46.80
Granted	180,337		$	59.43
Forfeited	(16,677	)	$	51.73
Vested	(169,896	)	$	53.35
Outstanding at December 31, 2017	201,081		$	52.18
Granted	242,780		$	36.87
Forfeited	(17,696	)	$	45.35
Vested	(194,459	)	$	45.16
Outstanding at December 31, 2018	231,706		$	42.55	$	33.08
Expected to vest	215,482		$	42.52	$	33.06

The following table presents the fair value of units vested and the unit-based liabilities paid for unit based awards related to the phantom units:



	Units	Fair Value of Units Vested		Unit-Based Liabilities Paid
		(millions)
Vested or paid in cash in 2016	126,681	$	4	$	5
Vested or paid in cash in 2017	169,896	$	7	$	4
Vested or paid in cash in 2018	194,459	$	5	$	7

Benefits	12 Months Ended
Benefits	Dec. 31, 2018
Retirement Benefits [Abstract]
Compensation and Employee Benefit Plans [Text Block]	16. Benefits We do not have our own employees. The employees supporting our operations are employees of DCP Services, LLC, for which we incur charges under the Services Agreement. All DCP Services, LLC employees who have reached the age of 18 and work at least 20 hours per week are eligible for participation in the 401(k) and retirement plan, to which a range of 4% to 7% of each eligible employee’s qualified earnings is contributed to the retirement plan, based on years of service. All new employees are automatically enrolled in the 401(k) plan at a 6% contribution level. Employees can opt out of these contribution level or change it at any time. Additionally, DCP Services, LLC matches employees’ contributions in the 401(k) plan up to 6% of qualified earnings. During the years ended December 31, 2018, 2017 and 2016, we expensed plan contributions of $30 million, $29 million and $29 million, respectively. DCP Services, LLC offers certain eligible executives the opportunity to participate in the EDC Plan. The EDC Plan allows participants to defer current compensation on a pre-tax basis and to receive tax deferred earnings on such contributions. The EDC Plan also has make-whole provisions for plan participants who may otherwise be limited in the amount that we can contribute to the 401(k) plan on the participant’s behalf.

Net Income or Loss per Limited Partner Unit	12 Months Ended
Net Income or Loss per Limited Partner Unit	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Income or Loss per Limited Partner Unit	17. Net Income or Loss per Limited Partner Unit Our net income or loss is allocated to the general partner and the limited partners in accordance with their respective ownership percentages, after allocating Available Cash generated during the period in accordance with our Partnership Agreement. Securities that meet the definition of a participating security are required to be considered for inclusion in the computation of basic earnings per unit using the two-class method. Under the two-class method, earnings per unit is calculated as if all of the earnings for the period were distributed under the terms of the Partnership Agreement, regardless of whether the general partner has discretion over the amount of distributions to be made in any particular period, whether those earnings would actually be distributed during a particular period from an economic or practical perspective, or whether the general partner has other legal or contractual limitations on its ability to pay distributions that would prevent it from distributing all of the earnings for a particular period. These required disclosures do not impact our overall net income or loss or other financial results; however, in periods in which aggregate net income exceeds our Available Cash it will have the impact of reducing net income per LPU. Basic and diluted net income or loss per LPU is calculated by dividing net income or loss allocable to limited partners, by the weighted-average number of LPUs outstanding during the period. Diluted net income or loss per LPU is computed based on the weighted average number of units plus the effect of potential dilutive units outstanding during the period using the two-class method.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

18. Income Taxes

We are structured as a master limited partnership with sufficient qualifying income, which is a pass-through entity for federal income tax purposes. We owned a corporation that filed its own federal, foreign and state corporate income tax returns. During the year ended December 31, 2016, we elected to convert the corporation to a limited liability company for federal income tax purposes. The income tax expense related to this corporation is included in our income tax expense, along with state and local taxes of the limited liability entities.

Income tax expense consists of the following:



	Year Ended December 31,
	2018			2017			2016
	(millions)
Current:
Federal income tax expense	$	—		$	—		$	(19	)
State income tax expense	—			(1		)	(2		)
Deferred:
Federal income tax expense	—			—			(22		)
State income tax expense	(3		)	(1		)	(3		)
Total income tax expense	$	(3	)	$	(2	)	$	(46	)

As of December 31, 2018 and 2017, we had state deferred tax liabilities of $32 million and $29 million, respectively. The state deferred tax liabilities are primarily associated with Texas franchise taxes. During the year ended December 31, 2016, we recorded a reduction to our net federal deferred tax asset of $58 million resulting from the conversion of our corporation to a limited liability company.

Our effective tax rate differs from statutory rates, primarily due to being structured as a master limited partnership, which is a pass-through entity for federal income tax purposes, while being treated as a taxable entity in certain states, primarily Texas. The State of Texas imposes a margin tax that is assessed at 0.75%, of taxable margin apportioned to Texas for each year ended December 31, 2018, 2017 and 2016.

Commitments and Contingent Liabilities

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingent Liabilities

Litigation — We are not a party to any significant legal proceedings, but are a party to various administrative and regulatory proceedings and commercial disputes that have arisen in the ordinary course of our business. Management currently believes that the ultimate resolution of the foregoing matters, taken as a whole, and after consideration of amounts accrued, insurance coverage or other indemnification arrangements, will not have a material adverse effect on our results of operations, financial position, or cash flow.

Insurance — Our insurance coverage is carried with third-party insurers and with an affiliate of Phillips 66. Our insurance coverage includes: (i) general liability insurance covering third-party exposures; (ii) statutory workers’ compensation insurance; (iii) automobile liability insurance for all owned, non-owned and hired vehicles; (iv) excess liability insurance above the established primary limits for general liability and automobile liability insurance; (v) property insurance, which covers the replacement value of real and personal property and includes business interruption; and (vi) insurance covering our directors and officers for acts related to our business activities. All coverage is subject to certain limits and deductibles, the terms and conditions of which are common for companies with similar types of operations.

Environmental — The operation of pipelines, plants and other facilities for gathering, transporting, processing, treating, fractionating, or storing natural gas, NGLs and other products is subject to stringent and complex laws and regulations pertaining to health, safety and the environment. As an owner or operator of these facilities, we must comply with laws and regulations at the federal, state and, in some cases, local levels that relate to worker safety, pipeline safety, air and water quality, solid and hazardous waste management and disposal, and other environmental matters. The cost of planning, designing, constructing and operating pipelines, plants, and other facilities incorporates compliance with environmental laws and regulations, worker safety standards, and safety standards applicable to our various facilities. In addition, there is increasing focus from (i) regulatory bodies and communities, and through litigation, on hydraulic fracturing and the real or perceived environmental or public health impacts of this technique, which indirectly presents some risk to our available supply of natural gas and the resulting supply of NGLs, (ii) regulatory bodies regarding pipeline system safety which could impose additional regulatory burdens and increase the cost of our operations, (iii) state and federal regulatory officials regarding the emission of greenhouse gases, which could impose regulatory burdens and increase the cost of our operations, and (iv) regulatory bodies and communities that could prevent or delay the development of fossil fuel energy infrastructure such as pipelines, plants, and other facilities used in our business. Failure to comply with these various health, safety and environmental laws and regulations may trigger a variety of administrative, civil and potentially criminal enforcement measures, including citizen suits, which can include the assessment of monetary penalties, the imposition of remedial requirements, and the issuance of injunctions or restrictions on operation. Management believes that, based on currently known information, compliance with these existing laws and regulations will not have a material adverse effect on our results of operations, financial position or cash flows.

We make expenditures in connection with environmental matters as part of our normal operations. As of December 31, 2018 and 2017, environmental liabilities included in our consolidated balance sheets as other current liabilities were $3 million and $4 million, respectively. As of December 31, 2018 and 2017, environmental liabilities included in our consolidated balance sheets as other long-term liabilities were $8 million and $8 million, respectively.

The following pending proceedings involve governmental authorities under federal, state, and local laws regulating the discharge of materials into the environment. It is not possible for us to predict the final outcome of these pending proceedings; however, we do not expect the outcome of one or more of these proceedings to have a material adverse effect to our results of operations, financial position, or cash flows:

•

In March 2018, the New Mexico Environment Department ("NMED") issued two separate Notices of Violation ("NOV") relating to upset and malfunction event emissions at two of our gas processing plants. Following information exchanges and discussions with NMED regarding the events and the propriety of the alleged violations, on February 14, 2019 we entered into preliminary settlement agreements to resolve the alleged violations under each NOV for administrative penalties in the amount of $149,832 and $142,233, respectively. We intend to mitigate a portion of each administrative penalty through the implementation of environmentally beneficial projects.

•

In April 2018, the Colorado Department of Public Health and Environment ("CDPHE") issued a Compliance Advisory in relation to an improperly permitted facility flare and related air emissions from flare operations at one of our gas processing plants that we self-disclosed to CDPHE in December 2017. Following information exchanges and discussions with CDPHE, during the first quarter of 2019, a resolution was proposed pursuant to which the plant's air permit would be revised to include the flare and emissions limits for such flare in addition to us paying an administrative penalty as well as an economic benefit payment generally covering the period when the flare was required to be included in the facility air permit, in a combined amount expected to be between approximately $195,000 and $240,000. We are still evaluating and holding discussions with CDPHE as to the foregoing amounts and proposed settlement terms.

Other Commitments and Contingencies — We utilize assets under operating leases in several areas of operation. Consolidated rental expense, including leases with no continuing commitment, totaled $30 million, $33 million and $37 million for the years ended December 31, 2018, 2017, and 2016, respectively. Rental expense for leases with escalation clauses is recognized on a straight line basis over the initial lease term.

Minimum rental payments under our various operating leases in the year indicated are as follows at December 31, 2018:



	Future Minimum Rental Payments as of December 31, 2018
	(millions)
2019	$	22
2020	18
2021	14
2022	9
2023	5
Thereafter	7
Total minimum rental payments	$	75

Business Segments

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Business Segments

Our operations are organized into two reportable segments: (i) Logistics and Marketing and (ii) Gathering and Processing. These segments are monitored separately by management for performance against our internal forecast and are consistent with internal financial reporting. These segments have been identified based on the differing products and services, regulatory environment and the expertise required for these operations. Our Gathering and Processing reportable segment includes operating segments that have been aggregated based on the nature of the products and services provided. Gross margin is a performance measure utilized by management to monitor the operations of each segment. The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies included in Note 2 - Summary of Significant Accounting Policies.

Our Logistics and Marketing segment includes transporting, trading, marketing, and storing natural gas and NGLs, fractionating NGLs, and wholesale propane logistics. Our Gathering and Processing segment consists of gathering, compressing, treating, processing natural gas, producing and fractionating NGLs, and recovering condensate. The remainder of our business operations is presented as “Other,” and consists of unallocated corporate costs. Elimination of inter-segment transactions are reflected in the eliminations column.

The following tables set forth our segment information:

Year Ended December 31, 2018:



	Logistics and Marketing			Gathering and Processing			Other			Eliminations			Total
	(millions)
Total operating revenue	$	9,014		$	5,843		$	—		$	(5,035	)	$	9,822
Gross margin (a)	$	225		$	1,578		$	—		$	—		$	1,803
Operating and maintenance expense	(47		)	(692		)	(21		)	—			(760		)
Depreciation and amortization expense	(15		)	(346		)	(27		)	—			(388		)
General and administrative expense	(12		)	(19		)	(245		)	—			(276		)
Asset impairments	—			(145		)	—			—			(145		)
Other expense, net	(4		)	(6		)	(1		)	—			(11		)
Loss from financing activities	—			—			(19		)	—			(19		)
Earnings from unconsolidated affiliates	362			8			—			—			370
Interest expense	—			—			(269		)	—			(269		)
Income tax expense	—			—			(3		)	—			(3		)
Net income (loss)	$	509		$	378		$	(585	)	$	—		$	302
Net income attributable to noncontrolling interests	—			(4		)	—			—			(4		)
Net income (loss) attributable to partners	$	509		$	374		$	(585	)	$	—		$	298
Non-cash derivative mark-to-market (b)	$	(4	)	$	112		$	—		$	—		$	108
Capital expenditures	$	8		$	570		$	17		$	—		$	595
Investments in unconsolidated affiliates, net	$	350		$	4		$	—		$	—		$	354

Year Ended December 31, 2017:



	Logistics and Marketing			Gathering and Processing			Other			Eliminations			Total
	(millions)
Total operating revenue	$	7,757		$	5,467		$	—		$	(4,762	)	$	8,462
Gross margin (a)	$	200		$	1,377		$	—		$	—		$	1,577
Operating and maintenance expense	(41		)	(602		)	(18		)	—			(661		)
Depreciation and amortization expense	(14		)	(343		)	(22		)	—			(379		)
General and administrative expense	(11		)	(19		)	(260		)	—			(290		)
Asset impairments	—			(48		)	—			—			(48		)
Other expense	(11		)	—			—			—			(11		)
Gain on sale of assets, net	—			34			—			—			34
Earnings from unconsolidated affiliates	243			60			—			—			303
Interest expense	—			—			(289		)	—			(289		)
Income tax expense	—			—			(2		)	—			(2		)
Net income (loss)	$	366		$	459		$	(591	)	$	—		$	234
Net income attributable to noncontrolling interests	—			(5		)	—			—			(5		)
Net income (loss) attributable to partners	$	366		$	454		$	(591	)	$	—		$	229
Non-cash derivative mark-to-market (b)	$	(4	)	$	(24	)	$	—		$	—		$	(28	)
Non-cash lower of cost or market adjustments	$	2		$	—		$	—		$	—		$	2
Capital expenditures	$	3		$	350		$	22		$	—		$	375
Investments in unconsolidated affiliates, net	$	147		$	1		$	—		$	—		$	148

Year Ended December 31, 2016:



	Logistics and Marketing			Gathering and Processing			Other			Eliminations			Total
	(millions)
Total operating revenue	$	6,186		$	4,490		$	—		$	(3,783	)	$	6,893
Gross margin (a)	$	205		$	1,227		$	—		$	—		$	1,432
Operating and maintenance expense	(43		)	(611		)	(16		)	—			(670		)
Depreciation and amortization expense	(15		)	(344		)	(19		)	—			(378		)
General and administrative expense	(9		)	(14		)	(269		)	—			(292		)
Other (expense) income	(5		)	73			(3		)	—			65
Gain on sale of assets, net	16			19			—			—			35
Restructuring costs	—			—			(13		)	—			(13		)
Earnings from unconsolidated affiliates	209			73			—			—			282
Interest expense	—			—			(321		)	—			(321		)
Income tax expense	—			—			(46		)	—			(46		)
Net income (loss)	$	358		$	423		$	(687	)	$	—		$	94
Net income attributable to noncontrolling interests	—			(6		)	—			—			(6		)
Net income (loss) attributable to partners	$	358		$	417		$	(687	)	$	—		$	88
Non-cash derivative mark-to-market (b)	$	(20	)	$	(119	)	$	—		$	—		$	(139	)
Non-cash lower of cost or market adjustments	$	3		$	—		$	—		$	—		$	3
Capital expenditures	$	10		$	107		$	27		$	—		$	144
Investments in unconsolidated affiliates, net	$	52		$	1		$	—		$	—		$	53



	December 31,		December 31,
	2018		2017
	(millions)
Segment long-term assets:
Gathering and Processing	$	9,058	$	8,943
Logistics and Marketing	3,661		3,348
Other (c)	276		265
Total long-term assets	12,995		12,556
Current assets	1,271		1,322
Total assets	$	14,266	$	13,878

(a)

Gross margin consists of total operating revenues, including commodity derivative activity, less purchases and related costs. Gross margin is viewed as a non-GAAP financial measure under the rules of the SEC, but is included as a supplemental disclosure because it is a primary performance measure used by management as it represents the results of product sales versus product purchases. As an indicator of our operating performance, gross margin should not be considered an alternative to, or more meaningful than, net income or net cash provided by operating activities as determined in accordance with GAAP. Our gross margin may not be comparable to a similarly titled measure of another company because other entities may not calculate gross margin in the same manner.


(b)	Non-cash commodity derivative mark-to-market is included in gross margin, along with cash settlements for our commodity derivative contracts.


(c)	Other long-term assets not allocable to segments consist of corporate leasehold improvements and other long-term assets.

Supplemental Cash Flow Information

12 Months Ended

Dec. 31, 2018

Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]

Supplemental Cash Flow Information



	Year Ended December 31,
	2018		2017		2016
	(millions)
Cash paid for interest:
Cash paid for interest, net of amounts capitalized	$	259	$	290	$	306
Cash paid for income taxes, net of income tax refunds	$	3	$	2	$	2
Non-cash investing and financing activities:
Property, plant and equipment acquired with accounts payable and accrued liabilities	$	99	$	58	$	27
Other non-cash changes in property, plant and equipment	$	5	$	5	$	(3	)

Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Data (Unaudited) [Abstract]

Quarterly Financial Information [Text Block]

23. Quarterly Financial Data (Unaudited)

Our consolidated results of operations by quarter for the years ended December 31, 2018 and 2017 were as follows:



2018	First			Second			Third			Fourth			Year ended December 31, 2018
	(millions, except per unit amounts)
Total operating revenues	$	2,139		$	2,317		$	2,759		$	2,607		$	9,822
Operating income	$	53		$	34		$	66		$	70		$	223
Net income	$	63		$	62		$	82		$	95		$	302
Net income attributable to noncontrolling interests	$	(1	)	$	(1	)	$	(1	)	$	(1	)	$	(4	)
Net income attributable to partners	$	62		$	61		$	81		$	94		$	298
Net income allocable to limited partners	$	12		$	10		$	26		$	39		$	87
Basic and diluted net income per limited partner unit	$	0.08		$	0.07		$	0.18		$	0.28		$	0.61



2017	First		Second			Third			Fourth			Year Ended December 31, 2017
	(millions, except per unit amounts)
Total operating revenues	$	2,121	$	1,949		$	2,055		$	2,337		$	8,462
Operating income (loss)	$	101	$	78		$	(19	)	$	62		$	222
Net income (loss)	$	101	$	89		$	(20	)	$	64		$	234
Net income attributable to noncontrolling interests	$	—	$	(1	)	$	—		$	(4	)	$	(5	)
Net income (loss) attributable to partners	$	101	$	88		$	(20	)	$	60		$	229
Net income allocable to limited partners	$	59	$	47		$	(59	)	$	14		$	61
Basic and diluted net income per limited partner unit	$	0.41	$	0.33		$	(0.41	)	$	0.10		$	0.43

Condensed Consolidating Financial Information

12 Months Ended

Dec. 31, 2018

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Condensed Consolidating Financial Information

The following condensed consolidating financial information presents the results of operations, financial position and cash flows of DCP Midstream, LP, or parent guarantor, DCP Midstream Operating LP, or subsidiary issuer, which is a 100% owned subsidiary, and non-guarantor subsidiaries, as well as the consolidating adjustments necessary to present DCP Midstream, LP’s results on a consolidated basis. The parent guarantor has agreed to fully and unconditionally guarantee debt securities of the subsidiary issuer. For the purpose of the following financial information, investments in subsidiaries are reflected in accordance with the equity method of accounting. The financial information may not necessarily be indicative of results of operations, cash flows, or financial position had the subsidiaries operated as independent entities.



	Condensed Consolidating Balance Sheets
	December 31, 2018
	Parent Guarantor		Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
ASSETS
Current assets:
Cash and cash equivalents	$	—	$	—		$	1		$	—		$	1
Accounts receivable, net	—		—			1,033			—			1,033
Inventories	—		—			79			—			79
Other	—		—			158			—			158
Total current assets	—		—			1,271			—			1,271
Property, plant and equipment, net	—		—			9,135			—			9,135
Goodwill and intangible assets, net	—		—			328			—			328
Advances receivable — consolidated subsidiaries	2,452		1,883			—			(4,335		)	—
Investments in consolidated subsidiaries	4,818		8,113			—			(12,931		)	—
Investments in unconsolidated affiliates	—		—			3,340			—			3,340
Other long-term assets	—		—			192			—			192
Total assets	$	7,270	$	9,996		$	14,266		$	(17,266	)	$	14,266
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	$	2	$	71		$	1,306		$	—		$	1,379
Current maturities of long-term debt	—		325			200			—			525
Advances payable — consolidated subsidiaries	—		—			4,335			(4,335		)	—
Long-term debt	—		4,782			—			—			4,782
Other long-term liabilities	—		—			283			—			283
Total liabilities	2		5,178			6,124			(4,335		)	6,969
Commitments and contingent liabilities
Equity:
Partners’ equity:
Net equity	7,268		4,821			8,118			(12,931		)	7,276
Accumulated other comprehensive loss	—		(3		)	(5		)	—			(8		)
Total partners’ equity	7,268		4,818			8,113			(12,931		)	7,268
Noncontrolling interests	—		—			29			—			29
Total equity	7,268		4,818			8,142			(12,931		)	7,297
Total liabilities and equity	$	7,270	$	9,996		$	14,266		$	(17,266	)	$	14,266



	Condensed Consolidating Balance Sheets
	December 31, 2017
	Parent Guarantor		Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
ASSETS
Current assets:
Cash and cash equivalents	$	—	$	155		$	1		$	—		$	156
Accounts receivable, net	—		—			981			—			981
Inventories	—		—			68			—			68
Other	—		—			117			—			117
Total current assets	—		155			1,167			—			1,322
Property, plant and equipment, net	—		—			8,983			—			8,983
Goodwill and intangible assets, net	—		—			337			—			337
Advances receivable — consolidated subsidiaries	2,895		1,614			—			(4,509		)	—
Investments in consolidated subsidiaries	4,513		7,522			—			(12,035		)	—
Investments in unconsolidated affiliates	—		—			3,050			—			3,050
Other long-term assets	—		—			186			—			186
Total assets	$	7,408	$	9,291		$	13,723		$	(16,544	)	$	13,878
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	$	—	$	71		$	1,417		$	—		$	1,488
Advances payable — consolidated subsidiaries	—		—			4,509			(4,509		)	—
Long-term debt	—		4,707			—			—			4,707
Other long-term liabilities	—		—			245			—			245
Total liabilities	—		4,778			6,171			(4,509		)	6,440
Commitments and contingent liabilities
Equity:
Partners’ equity:
Net equity	7,408		4,517			7,527			(12,035		)	7,417
Accumulated other comprehensive loss	—		(4		)	(5		)	—			(9		)
Total partners’ equity	7,408		4,513			7,522			(12,035		)	7,408
Noncontrolling interests	—		—			30			—			30
Total equity	7,408		4,513			7,552			(12,035		)	7,438
Total liabilities and equity	$	7,408	$	9,291		$	13,723		$	(16,544	)	$	13,878



	Condensed Consolidating Statement of Operations
	Year Ended December 31, 2018
	Parent Guarantor		Subsidiary Issuer			Non- Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Operating revenues:
Sales of natural gas, NGLs and condensate	$	—	$	—		$	9,374		$	—		$	9,374
Transportation, processing and other	—		—			489			—			489
Trading and marketing losses, net	—		—			(41		)	—			(41		)
Total operating revenues	—		—			9,822			—			9,822
Operating costs and expenses:
Purchases and related costs	—		—			8,019			—			8,019
Operating and maintenance expense	—		—			760			—			760
Depreciation and amortization expense	—		—			388			—			388
General and administrative expense	—		—			276			—			276
Asset impairments	—		—			145			—			145
Other expense, net	—		—			11			—			11
Total operating costs and expenses	—		—			9,599			—			9,599
Operating income	—		—			223			—			223
Loss from financing activities	—		(19		)	—			—			(19		)
Interest expense, net	—		(268		)	(1		)	—			(269		)
Income from consolidated subsidiaries	298		585			—			(883		)	—
Earnings from unconsolidated affiliates	—		—			370			—			370
Income before income taxes	298		298			592			(883		)	305
Income tax expense	—		—			(3		)	—			(3		)
Net income	298		298			589			(883		)	302
Net income attributable to noncontrolling interests	—		—			(4		)	—			(4		)
Net income attributable to partners	$	298	$	298		$	585		$	(883	)	$	298



	Condensed Consolidating Statement of Comprehensive Income
	Year Ended December 31, 2018
	Parent Guarantor		Subsidiary Issuer		Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Net income	$	298	$	298	$	589		$	(883	)	$	302
Other comprehensive income:
Reclassification of cash flow hedge losses into earnings	—		1		—			—			1
Other comprehensive income from consolidated subsidiaries	1		—		—			(1		)	—
Total other comprehensive income	1		1		—			(1		)	1
Total comprehensive income	299		299		589			(884		)	303
Total comprehensive income attributable to noncontrolling interests	—		—		(4		)	—			(4		)
Total comprehensive income attributable to partners	$	299	$	299	$	585		$	(884	)	$	299



	Condensed Consolidating Statement of Operations
	Year Ended December 31, 2017
	Parent Guarantor		Subsidiary Issuer			Non- Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Operating revenues:
Sales of natural gas, NGLs and condensate	$	—	$	—		$	7,850		$	—		$	7,850
Transportation, processing and other	—		—			652			—			652
Trading and marketing losses, net	—		—			(40		)	—			(40		)
Total operating revenues	—		—			8,462			—			8,462
Operating costs and expenses:
Purchases and related costs	—		—			6,885			—			6,885
Operating and maintenance expense	—		—			661			—			661
Depreciation and amortization expense	—		—			379			—			379
General and administrative expense	—		—			290			—			290
Asset impairments	—		—			48			—			48
Gain on sale of assets, net	—		—			(34		)	—			(34		)
Other expense, net	—		—			11			—			11
Total operating costs and expenses	—		—			8,240			—			8,240
Operating income	—		—			222			—			222
Interest expense, net	—		(289		)	—			—			(289		)
Income from consolidated subsidiaries	229		518			—			(747		)	—
Earnings from unconsolidated affiliates	—		—			303			—			303
Income before income taxes	229		229			525			(747		)	236
Income tax expense	—		—			(2		)	—			(2		)
Net income	229		229			523			(747		)	234
Net income attributable to noncontrolling interests	—		—			(5		)	—			(5		)
Net income attributable to partners	$	229	$	229		$	518		$	(747	)	$	229



	Condensed Consolidating Statement of Comprehensive Income
	Year Ended December 31, 2017
	Parent Guarantor		Subsidiary Issuer		Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Net income	$	229	$	229	$	523		$	(747	)	$	234
Other comprehensive income:
Reclassification of cash flow hedge losses into earnings	—		1		—			—			1
Other comprehensive income from consolidated subsidiaries	1		—		—			(1		)	—
Total other comprehensive income	1		1		—			(1		)	1
Total comprehensive income	230		230		523			(748		)	235
Total comprehensive income attributable to noncontrolling interests	—		—		(5		)	—			(5		)
Total comprehensive income attributable to partners	$	230	$	230	$	518		$	(748	)	$	230



	Condensed Consolidating Statement of Operations
	Year Ended December 31, 2016
	Parent Guarantor		Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Operating revenues:
Sales of natural gas, NGLs and condensate	$	—	$	—		$	6,269		$	—		$	6,269
Transportation, processing and other	—		—			647			—			647
Trading and marketing losses, net	—		—			(23		)	—			(23		)
Total operating revenues	—		—			6,893			—			6,893
Operating costs and expenses:
Purchases and related costs	—		—			5,461			—			5,461
Operating and maintenance expense	—		—			670			—			670
Depreciation and amortization expense	—		—			378			—			378
General and administrative expense	—		—			292			—			292
Gain on sale of assets, net	—		—			(35		)	—			(35		)
Restructuring costs	—		—			13			—			13
Other income, net	—		—			(65		)	—			(65		)
Total operating costs and expenses	—		—			6,714			—			6,714
Operating income	—		—			179			—			179
Interest expense, net	—		(321		)	—			—			(321		)
Income from consolidated subsidiaries	88		409			—			(497		)	—
Earnings from unconsolidated affiliates	—		—			282			—			282
Income before income taxes	88		88			461			(497		)	140
Income tax expense	—		—			(46		)	—			(46		)
Net income	88		88			415			(497		)	94
Net income attributable to noncontrolling interests	—		—			(6		)	—			(6		)
Net income attributable to partners	$	88	$	88		$	409		$	(497	)	$	88



	Condensed Consolidating Statement of Comprehensive Income
	Year Ended December 31, 2016
	Parent Guarantor		Subsidiary Issuer		Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Net income	$	88	$	88	$	415		$	(497	)	$	94
Other comprehensive income:
Total other comprehensive income	—		—		—			—			—
Total comprehensive income	88		88		415			(497		)	94
Total comprehensive income attributable to noncontrolling interests	—		—		(6		)	—			(6		)
Total comprehensive income attributable to partners	$	88	$	88	$	409		$	(497	)	$	88



	Condensed Consolidating Statement of Cash Flows
	Year Ended December 31, 2018
	Parent Guarantor			Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$	—		$	(263	)	$	925		$	—		$	662
INVESTING ACTIVITIES:
Intercompany transfers	443			(269		)	—			(174		)	—
Capital expenditures	—			—			(595		)	—			(595		)
Investments in unconsolidated affiliates, net	—			—			(354		)	—			(354		)
Proceeds from sale of assets	—			—			4			—			4
Net cash provided by (used in) investing activities	443			(269		)	(945		)	(174		)	(945		)
FINANCING ACTIVITIES:
Intercompany transfers	—			—			(174		)	174			—
Proceeds from debt	—			4,961			200			—			5,161
Payments of debt	—			(4,560		)	—			—			(4,560		)
Costs incurred to redeem senior notes	—			(18		)	—			—			(18		)
Proceeds from issuance of preferred limited partner units, net of offering costs	261			—			—			—			261
Distributions to preferred limited partners	(46		)	—			—			—			(46		)
Distributions to limited partners and general partner	(658		)	—			—			—			(658		)
Distributions to noncontrolling interests	—			—			(5		)	—			(5		)
Other	—			(6		)	(1		)	—			(7		)
Net cash (used in) provided by financing activities	(443		)	377			20			174			128
Net change in cash and cash equivalents	—			(155		)	—			—			(155		)
Cash and cash equivalents, beginning of period	—			155			1			—			156
Cash and cash equivalents, end of period	$	—		$	—		$	1		$	—		$	1



	Condensed Consolidating Statements of Cash Flows
	Year Ended December 31, 2017
	Parent Guarantor			Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$	—		$	(283	)	$	1,179		$	—		$	896
INVESTING ACTIVITIES:
Intercompany transfers	58			1,141			—			(1,199		)	—
Capital expenditures	—			—			(375		)	—			(375		)
Investments in unconsolidated affiliates, net	—			—			(148		)	—			(148		)
Proceeds from sale of assets	—			—			132			—			132
Net cash provided by (used in) investing activities	58			1,141			(391		)	(1,199		)	(391		)
FINANCING ACTIVITIES:
Intercompany transfers	—			—			(1,199		)	1,199			—
Proceeds from long-term debt	—			116			—			—			116
Payments of debt	—			(811		)	—			—			(811		)
Proceeds from issuance of preferred limited partner units, net of offering costs	487			—			—			—			487
Net change in advances to predecessor from DCP Midstream, LLC	—			—			418			—			418
Distributions to limited partners and general partner	(545		)	—			—			—			(545		)
Distributions to noncontrolling interests	—			—			(7		)	—			(7		)
Other	—			(8		)	—			—			(8		)
Net cash used in financing activities	(58		)	(703		)	(788		)	1,199			(350		)
Net change in cash and cash equivalents	—			155			—			—			155
Cash and cash equivalents, beginning of period	—			—			1			—			1
Cash and cash equivalents, end of period	$	—		$	155		$	1		$	—		$	156



	Condensed Consolidating Statements of Cash Flows
	Year Ended December 31, 2016
	Parent Guarantor			Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$	—		$	(305	)	$	950		$	—		$	645
INVESTING ACTIVITIES:
Intercompany transfers	483			585			—			(1,068		)	—
Capital expenditures	—			—			(144		)	—			(144		)
Investments in unconsolidated affiliates, net	—			—			(53		)	—			(53		)
Proceeds from sale of assets	—			—			163			—			163
Net cash (used in) provided by investing activities	483			585			(34		)	(1,068		)	(34		)
FINANCING ACTIVITIES:
Intercompany transfers	—			—			(1,068		)	1,068			—
Proceeds from long-term debt	—			3,353			—			—			3,353
Payments of long-term debt	—			(3,628		)	—			—			(3,628		)
Net change in advances to predecessor from DCP Midstream, LLC	—			—			157			—			157
Distributions to limited partners and general partner	(483		)	—			—			—			(483		)
Distributions to noncontrolling interests	—			—			(7		)	—			(7		)
Other	—			(5		)	—			—			(5		)
Net cash provided by (used in) financing activities	(483		)	(280		)	(918		)	1,068			(613		)
Net change in cash and cash equivalents	—			—			(2		)	—			(2		)
Cash and cash equivalents, beginning of year	—			—			3			—			3
Cash and cash equivalents, end of year	$	—		$	—		$	1		$	—		$	1

- Definition

The entire disclosure for condensed financial information, including the financial position, cash flows, and the results of operations of the registrant (parent company) as of the same dates or for the same periods for which audited consolidated financial statements are being presented. Alternatively, the details of this disclosure can be reported by the specific parent company taxonomy elements, indicating the appropriate date and period contexts in an instance document.

+ References + Details

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 23, 2019, we announced that the board of directors of the General Partner declared a quarterly distribution on our common units of $0.78 per common unit. The distribution will be paid on February 14, 2019 to unitholders of record on February 4, 2019. On the same date, the board of directors of the General Partner declared a quarterly distribution on our Series B and Series C Preferred Units of $0.4922 and $0.4969 per unit, respectively. The Series B distributions will be paid on March 15, 2019 to unitholders of record on March 1, 2019. The Series C distribution will be paid on April 15, 2019 to unitholders of record on April 1, 2019. On January 18, 2019, we issued $325 million of additional aggregate principal amount to our existing $500 million 5.375% Senior Notes due July 2025. The full $825 million 5.375% Senior Notes due July 2025 will be treated as a single series of debt. We received proceeds of $324 million, net of underwriters’ fees, related expenses and issuance premiums, which we expect to use for general partnership purposes including the funding of capital expenditures and repayment of outstanding indebtedness under the Credit Agreement. Interest on the notes will be paid semi-annually in arrears on the 15th day of January and July of each year, with the initial interest payment on July 15, 2019. On January 30, 2019, we entered into a purchase and sale agreement with NGL Energy Partners LP to sell Gas Supply Resources, our wholesale propane business primarily consisting of seven natural gas liquids terminals in the Eastern United States within our Logistics and Marketing segment for approximately $90 million, subject to customary purchase price adjustments. The transaction is expected to close effective March 1, 2019. We expect to recognize a loss on sale of approximately $8 million, net of goodwill, in the first quarter of 2019.

Description of Business and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP.
Equity Method Investments	Investments in greater than 20% owned affiliates that are not variable interest entities and where we do not have the ability to exercise control, and investments in less than 20% owned affiliates where we have the ability to exercise significant influence, are accounted for using the equity method. Investments in greater than 20% owned affiliates that are not variable interest entities and where we do not have the ability to exercise control, and investments in less than 20% owned affiliates where we have the ability to exercise significant influence, are accounted for using the equity method. Investments in Unconsolidated Affiliates - We use the equity method to account for investments in greater than 20% owned affiliates. We evaluate our investments in unconsolidated affiliates for impairment whenever events or changes in circumstances indicate that the carrying value of such investments may have experienced a decline in value. When there is evidence of loss in value that is other than temporary, we compare the estimated fair value of the investment to the carrying value of the investment to determine whether impairment has occurred. We assess the fair value of our investments in unconsolidated affiliates using commonly accepted techniques, and may use more than one method, including, but not limited to, recent third party comparable sales and discounted cash flow models. If the estimated fair value is less than the carrying value, the excess of the carrying value over the estimated fair value is recognized as an impairment loss.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Business Description and Basis of Presentation [Text Block]

The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates, Policy [Policy Text Block]

Cash, Cash Equivalents, and Marketable Securities [Text Block]

Allowance for Doubtful Accounts [Policy Text Block]

Inventory, Policy [Policy Text Block]

Inventories - Inventories, which consist primarily of NGLs and natural gas, are recorded at the lower of weighted-average cost or market value. Transportation costs are included in inventory.

Accounting for Risk Management Activities and Financial Instruments



Classification of Contract	Accounting Method	Presentation of Gains & Losses or Revenue & Expense
Trading Derivatives	Mark-to-market method (a)	Net basis in trading and marketing gains and losses
Non-Trading Derivatives:
Cash Flow Hedge	Hedge method (b)	Gross basis in the same consolidated statements of operations category as the related hedged item

Fair Value Hedge	Hedge method (b)	Gross basis in the same consolidated statements of operations category as the related hedged item

Normal Purchases or Normal Sales	Accrual method (c)	Gross basis upon settlement in the corresponding consolidated statements of operations category based on purchase or sale

Other Non-Trading Derivative Activity	Mark-to-market method (a)	Net basis in trading and marketing gains and losses, net


(a)	Mark-to-market method - An accounting method whereby the change in the fair value of the asset or liability is recognized in the consolidated statements of operations in trading and marketing gains and losses, net during the current period.

(b)


(c)	Accrual method - An accounting method whereby there is no recognition in the consolidated balance sheets or consolidated statements of operations for changes in fair value of a contract until the service is provided or the associated delivery impacts earnings.

Cash Flow and Fair Value Hedges

Valuation

Property, Plant and Equipment, Policy [Policy Text Block]

Interest Capitalization, Policy [Policy Text Block]

Asset Retirement Obligation [Policy Text Block]

Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]

Investments in Unconsolidated Affiliates, Policy

Investments in greater than 20% owned affiliates that are not variable interest entities and where we do not have the ability to exercise control, and investments in less than 20% owned affiliates where we have the ability to exercise significant influence, are accounted for using the equity method.

Investments in Unconsolidated Affiliates - We use the equity method to account for investments in greater than 20% owned affiliates.

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]


•	significant adverse change in legal factors or business climate;


•	a current-period operating or cash flow loss combined with a history of operating or cash flow losses, or a projection or forecast that demonstrates continuing losses associated with the use of a long-lived asset;


•	an accumulation of costs significantly in excess of the amount originally expected for the acquisition or construction of a long-lived asset;


•	significant adverse changes in the extent or manner in which an asset is used, or in its physical condition;


•	a significant adverse change in the market value of an asset; or


•	a current expectation that, more likely than not, an asset will be sold or otherwise disposed of before the end of its estimated useful life.

Unamortized Debt Discount and Expense (Policy)

Noncontrolling Interest (Policy)

Revenue Recognition, Policy [Policy Text Block]

Revenue Recognition - Our operating revenues are primarily derived from the following activities:


•	sales of natural gas, NGLs and condensate;


•	services related to gathering, compressing, treating, and processing natural gas; and


•	services related to transportation and storage of natural gas and NGLs.

Transportation and storage - Revenue from transportation and storage agreements is recognized based on contracted volumes transported and stored in the period the services are provided.

Contract Liabilities (Policy)

Purchases and Related Costs (Policy)

Major Customers, Policy [Policy Text Block]

Environmental Costs, Policy [Policy Text Block]

Equity-Based Compensation Policy)

Income Tax, Policy [Policy Text Block]

Net Income or Loss per Limited Partners Unit (Policy)

Revenue Recognition (Tables)

12 Months Ended

Dec. 31, 2018

Disaggregation of Revenue [Line Items]

Disaggregation of Revenue [Table Text Block]



	Year Ended December 31, 2018
	Gathering and Processing		Logistics and Marketing			Eliminations			Total
	(millions)
Sales of natural gas	$	1,955	$	2,325		$	(1,752	)	$	2,528
Sales of NGLs and condensate (a)	3,437		6,692			(3,283		)	6,846
Transportation, processing and other	432		57			—			489
Trading and marketing losses, net (b)	19		(60		)	—			(41		)
Total operating revenues	$	5,843	$	9,014		$	(5,035	)	$	9,822

(a) Includes $4,347 million of revenues from physical sales contracts and buy-sell exchange transactions in our logistics and marketing segment, which are not within the scope of Topic 606.

(b) Not within the scope of Topic 606.

Agreements and Transactions with Affiliates (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Fees Incurred and Other Fees Paid

The following table summarizes employee related costs that were charged by DCP Midstream, LLC to the Partnership that are included in the consolidated statements of operations:



		Year Ended December 31,
		2018		2017		2016
	(millions)
Employee related costs charged by DCP Midstream, LLC
Operating and maintenance expense		$	209	$	197	$	206
General and administrative expense		$	187	$	182	$	197

Summary of Transactions with Affiliates

The following table summarizes our transactions with affiliates:



		Year Ended December 31,
		2018		2017		2016
	(millions)
Phillips 66 (including its affiliates):
Sales of natural gas, NGLs and condensate to affiliates		$	1,534	$	1,172	$	909
Purchases and related costs from affiliates		$	138	$	30	$	18
Operating and maintenance and general administrative expenses		$	13	$	2	$	2
Enbridge (including its affiliates):
Sales of natural gas, NGLs and condensate to affiliates		$	11	$	48	$	—
Purchases and related costs from affiliates		$	35	$	43	$	33
Operating and maintenance and general administrative expenses		$	—	$	2	$	4
Unconsolidated affiliates:
Sales of natural gas, NGLs and condensate to affiliates		$	65	$	54	$	43
Transportation, processing, and other to affiliates		$	6	$	5	$	5
Purchases and related costs from affiliates		$	723	$	504	$	432

We had balances with affiliates as follows:



	December 31, 2018		December 31, 2017
	(millions)
Phillips 66 (including its affiliates):
Accounts receivable	$	145	$	156
Accounts payable	$	22	$	6
Other assets	$	—	$	—
Enbridge (including its affiliates):
Accounts receivable	$	—	$	11
Accounts payable	$	2	$	9
Unconsolidated affiliates:
Accounts receivable	$	21	$	24
Accounts payable	$	72	$	53
Other assets	$	—	$	4

Inventories (Tables)

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Schedule of Inventories

Inventories were as follows:



	December 31, 2018		December 31, 2017
	(millions)
Natural gas	$	34	$	30
NGLs	45		38
Total inventories	$	79	$	68

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Classification of Property, Plant and Equipment

A summary of property, plant and equipment by classification is as follows:



	Depreciable Life	December 31, 2018			December 31, 2017
		(millions)
Gathering and transmission systems	20 — 50 Years	$	8,492		$	8,473
Processing, storage and terminal facilities	35 — 60 Years	5,194			5,128
Other	3 — 30 Years	568			557
Construction work in progress		470			374
Property, plant and equipment		14,724			14,532
Accumulated depreciation		(5,589		)	(5,549		)
Property, plant and equipment, net		$	9,135		$	8,983

Asset Retirement Obligation Disclosure [Text Block]

Asset Retirement Obligations

The following table summarizes changes in the asset retirement obligations included in our balance sheets:



	December 31,
	2018 (a)		2017 (a)
	(millions)
Balance, beginning of period	$	126	$	124
Accretion expense	8		8
Change in ARO Estimate	6		(6		)
Balance, end of period	$	140	$	126

Goodwill (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill [Line Items]

Schedule of Goodwill [Table Text Block]

The carrying amount of goodwill in each of our reportable segments was as follows:




	December 31, 2018						December 31, 2017
	(millions)
	Gathering and Processing		Logistics and Marketing		Total		Gathering and Processing			Logistics and Marketing		Total
Balance, beginning of period	$	159	$	72	$	231	$	164		$	72	$	236
Dispositions	—		—		—		(5		)	—		(5		)
Balance, end of period	$	159	$	72	$	231	$	159		$	72	$	231

Schedule of Finite-Lived Intangible Assets [Table Text Block]

Estimated future amortization for these intangible assets is as follows:



Estimated Future Amortization
(millions)
2019	$	9
2020	9
2021	9
2022	9
2023	8
Thereafter	53
Total	$	97



	December 31,			December 31,
	2018			2017
	(millions)
Gross carrying amount	$	410		$	410
Accumulated amortization	(170		)	(161		)
Accumulated impairment	(143		)	(143		)
Intangible assets, net	$	97		$	106

Investments in Unconsolidated Affiliates (Tables)

12 Months Ended

Dec. 31, 2018

Equity Method Investments and Joint Ventures [Abstract]

Investments in Unconsolidated Affiliates

The following table summarizes our investments in unconsolidated affiliates:



		Carrying Value as of
	Percentage Ownership	December 31, 2018		December 31, 2017
		(millions)
DCP Sand Hills Pipeline, LLC	66.67%	$	1,791	$	1,633
DCP Southern Hills Pipeline, LLC	66.67%	728		739
Discovery Producer Services LLC	40.00%	344		362
Front Range Pipeline LLC	33.33%	175		165
Texas Express Pipeline LLC	10.00%	95		90
Gulf Coast Express Pipeline LLC	25.00%	146		—
Mont Belvieu Enterprise Fractionator	12.50%	24		23
Panola Pipeline Company, LLC	15.00%	23		24
Mont Belvieu 1 Fractionator	20.00%	10		10
Other	Various	4		4
Total investments in unconsolidated affiliates		$	3,340	$	3,050

Schedule of Excess (Deficit) of Carrying Value of Investment in Unconsolidated Affliate [Table Text Block]



	Excess (deficit) of Carrying Value over (under) Underlying Equity in Unconsolidated Affiliates
	December 31, 2018			December 31, 2017
	(millions)
DCP Sand Hills Pipeline, LLC	$	634		$	648
Discovery Producer Services LLC	(15		)	(18		)
DCP Southern Hills Pipeline, LLC	142			145
Front Range Pipeline LLC	4			4
Texas Express Pipeline LLC	3			3
Mont Belvieu 1 Fractionator	—			(1		)

Carrying amounts in excess or deficit of the underlying equity of our unconsolidated affiliates are amortized over the life of the underlying long-lived assets of the affiliate.

Schedule Of Earnings From Investment In Unconsolidated Affiliates [Table Text Block]

Earnings from investments in unconsolidated affiliates were as follows:



		Year Ended December 31,
		2018		2017		2016
	(millions)
DCP Sand Hills Pipeline, LLC		$	223	$	148	110
DCP Southern Hills Pipeline, LLC		68		47		44
Discovery Producer Services LLC		8		61		73
Front Range Pipeline LLC		24		17		19
Texas Express Pipeline LLC		19		9		9
Mont Belvieu Enterprise Fractionator		10		13		16
Mont Belvieu 1 Fractionator		16		6		9
Other		2		2		2
Total earnings from unconsolidated affiliates		$	370	$	303	$	282

Equity Method Investment Summarized Financial Information, Statement of Operations [Table Text Block]

The following tables summarize the combined financial information of our investments in unconsolidated affiliates:



	Year Ended December 31,
	2018		2017		2016
	(millions)
Statements of operations:
Operating revenue	$	1,560	$	1,397	$	1,311
Operating expenses	$	613	$	647	$	539
Net income	$	945	$	747	$	768

Equity Method Investment Summarized Financial Information Balance Sheet Table [Table Text Block]



	December 31, 2018			December 31, 2017
	(millions)
Balance sheets:
Current assets	$	411		$	244
Long-term assets	6,359			5,319
Current liabilities	(424		)	(196		)
Long-term liabilities	(221		)	(200		)
Net assets	$	6,125		$	5,167

Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Impaired Assets



	December 31, 2018				December 31, 2017
	Net Carrying Value		Asset Impairments		Net Carrying Value		Asset Impairments
	Net Carrying Value		Asset Impairments		Net Carrying Value		Asset Impairments
	(millions)
Property, plant and equipment	$	15	$	145	$	14	$	26
Intangible assets	—		—		11		21
Investment in unconsolidated affiliates	—		—		1		1
Total impairments	$	15	$	145	$	26	$	48

The following table presents the financial instruments carried at fair value as of

Financial Instruments Carried at Fair Value



	December 31, 2018												December 31, 2017
	Level 1			Level 2			Level 3			Total Carrying Value			Level 1			Level 2			Level 3			Total Carrying Value
	(millions)
Current assets:
Commodity derivatives (a)	$	62		$	32		$	14		$	108		$	10		$	17		$	3		$	30
Short-term investments (b)	$	—		$	—		$	—		$	—		$	156		$	—		$	—		$	156
Long-term assets:
Commodity derivatives (c)	$	4		$	2		$	2		$	8		$	1		$	1		$	1		$	3
Current liabilities:
Commodity derivatives (d)	$	(39	)	$	(52	)	$	—		$	(91	)	$	(29	)	$	(34	)	$	(13	)	$	(76	)
Long-term liabilities:
Commodity derivatives (e)	$	(1	)	$	(5	)	$	(2	)	$	(8	)	$	(3	)	$	(11	)	$	(1	)	$	(15	)


(a)	Included in current unrealized gains on derivative instruments in our consolidated balance sheets.


(b)	Includes short-term money market securities included in cash and cash equivalents in our consolidated balance sheets.


(c)	Included in long-term unrealized gains on derivative instruments in our consolidated balance sheets.


(d)	Included in current unrealized losses on derivative instruments in our consolidated balance sheets.


(e)	Included in long-term unrealized losses on derivative instruments in our consolidated balance sheets.

Fair Value Assets and Liabilities Measured On Recurring Basis Unobservable Input Reconciliation



	Commodity Derivative Instruments
	Current Assets			Long-Term Assets			Current Liabilities			Long-Term Liabilities
	(millions)
Year ended December 31, 2018 (a):
Beginning balance	$	3		$	1		$	(13	)	$	(1	)
Net unrealized gains (losses) included in earnings (b)	14			1			(6		)	(1		)
Settlements	(3		)	—			19			—
Ending balance	$	14		$	2		$	—		$	(2	)
Net unrealized gains (losses) on derivatives still held included in earnings (b)	$	14		$	1		$	—		$	(1	)
Year ended December 31, 2017 (a):
Beginning balance	$	9		$	5		$	(23	)	$	—
Net unrealized gains (losses) included in earnings (b)	14			1			(44		)	(3		)
Transfers out of Level 3 (c)	—			—			—			2
Settlements	(13		)	—			36			—
CME Rule 814 adjustment	(7		)	(5		)	18			—
Ending balance	$	3		$	1		$	(13	)	$	(1	)
Net unrealized gains (losses) on derivatives still held included in earnings (b)	$	3		$	(4	)	$	(13	)	$	(1	)


(a)	There were no purchases, issuances or sales of derivatives or transfers into Level 3 for the three and years ended December 31, 2018 and 2017.


(b)	Represents the amount of unrealized gains or losses for the period, included in trading and marketing gains (losses), net.


(c)	Amounts transferred out of Level 3 are reflected at fair value at the end of the period.

Schedule of Valuation Processes



	December 31, 2018
Product Group	Fair Value			Forward Curve Range
	(millions)
Assets
NGLs	$	14		$0.31-$0.96	Per gallon
Natural gas	$	2		$2.01-$2.56	Per MMBtu
Liabilities
Natural gas	$	(2	)	$2.46-$2.88	Per MMBtu

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]



		December 31, 2018				December 31, 2017
		Carrying Value (a)		Fair Value		Carrying Value (a)		Fair Value
	(millions)

Total debt		$	5,337	$	5,170	$	4,736	$	4,885

(a) Excludes unamortized issuance costs.

Debt (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Schedule of Debt



	December 31, 2018			December 31, 2017
	(millions)
Senior notes:
Issued February 2009, interest at 9.750% payable semiannually, due March 2019 (a)	$	—		$	450
Issued March 2014, interest at 2.700% payable semi-annually, due April 2019	325			325
Issued March 2010, interest at 5.350% payable semiannually, due March 2020 (a)	600			600
Issued September 2011, interest at 4.750% payable semiannually, due September 2021	500			500
Issued March 2012, interest at 4.950% payable semi-annually, due April 2022	350			350
Issued March 2013, interest at 3.875% payable semi-annually, due March 2023	500			500
Issued July 2018, interest at 5.375% payable semi-annually, due July 2025	500			—
Issued August 2000, interest at 8.125% payable semi-annually, due August 2030 (a)	300			300
Issued October 2006, interest at 6.450% payable semi-annually, due November 2036	300			300
Issued September 2007, interest at 6.750% payable semi-annually, due September 2037	450			450
Issued March 2014, interest at 5.600% payable semi-annually, due April 2044	400			400
Junior subordinated notes:
Issued May 2013, interest at 5.850% payable semi-annually, due May 2043	550			550
Credit agreement:
Revolving credit facility, weighted-average variable interest rate of 3.901%, as of December 31, 2018, due December 2022	351			—
Accounts receivable securitization facility:
Accounts receivable securitization facility, weighted-average variable interest rate of 3.303% as of December 31, 2018, due August 2019	200			—
Fair value adjustments related to interest rate swap fair value hedges (a)	21			23
Unamortized issuance costs	(30		)	(29		)
Unamortized discount	(10		)	(12		)
Total debt	5,307			4,707
Current debt	525			—
Total long-term debt	$	4,782		$	4,707

(a) The swaps associated with this debt were previously terminated. The remaining long-term fair value of approximately

$21 million related to the swaps is being amortized as a reduction to interest expense through 2020 and 2030, the original maturity dates of the debt.

Future Maturities of Long-Term Debt

The maturities of our debt as of December 31, 2018 are as follows:



	Debt Maturities
	(millions)
2019	$	525
2020	600
2021	500
2022	701
2023	500
Thereafter	2,500
Total debt	$	5,326

Risk Management and Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Summary of Gross and Net Amounts of Derivative Instruments



	December 31, 2018								December 31, 2017
	Gross Amounts of Assets and (Liabilities) Presented in the Balance Sheet			Amounts Not Offset in the Balance Sheet - Financial Instruments		Net Amount			Gross Amounts of Assets and (Liabilities) Presented in the Balance Sheet			Amounts Not Offset in the Balance Sheet - Financial Instruments		Net Amount
	(millions)
Assets:
Commodity derivatives	$	116		$	—	$	116		$	33		$	—	$	33
Liabilities:
Commodity derivatives	$	(99	)	$	—	$	(99	)	$	(91	)	$	—	$	(91	)

Schedule of Designated and Non-Designated Derivative Instruments in Statement of Financial Position, Fair Value



Balance Sheet Line Item	December 31, 2018		December 31, 2017		Balance Sheet Line Item	December 31, 2018			December 31, 2017
	(millions)					(millions)
Derivative Assets Not Designated as Hedging Instruments:					Derivative Liabilities Not Designated as Hedging Instruments:
Commodity derivatives:					Commodity derivatives:
Unrealized gains on derivative instruments — current	$	108	$	30	Unrealized losses on derivative instruments — current	$	(91	)	$	(76	)
Unrealized gains on derivative instruments — long-term	8		3		Unrealized losses on derivative instruments — long-term	(8		)	(15		)
Total	$	116	$	33	Total	$	(99	)	$	(91	)

Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]

The following summarizes the balance and activity within AOCI relative to our interest rate, commodity and foreign currency cash flow hedges as of and for the year ended December 31, 2018:



	Interest Rate Cash Flow Hedges			Commodity Cash Flow Hedges			Foreign Currency Cash Flow Hedges (a)		Total
	(millions)
Net deferred (losses) gains in AOCI (beginning balance)	$	(4	)	$	(6	)	$	1	$	(9	)
Losses reclassified from AOCI to earnings — effective portion	1			—			—		1
Net deferred (losses) gains in AOCI (ending balance)	$	(3	)	$	(6	)	$	1	$	(8	)
Deferred losses in AOCI expected to be reclassified into earnings over the next 12 months	$	(1	)	$	—		$	—	$	(1	)

(a)Relates to Discovery Producer Services LLC ("Discovery"), an unconsolidated affiliate.

The following summarizes the balance and activity within AOCI relative to our interest rate, commodity and foreign currency cash flow hedges as of and for the year ended December 31, 2017:



	Interest Rate Cash Flow Hedges			Commodity Cash Flow Hedges			Foreign Currency Cash Flow Hedges (a)		Total
	(millions)
Net deferred (losses) gains in AOCI (beginning balance)	$	(3	)	$	(6	)	$	1	$	(8	)
Losses reclassified from AOCI to earnings — effective portion	1			—			—		1
Deficit purchase price under carrying value	(2		)	—			—		(2		)
Net deferred (losses) gains in AOCI (ending balance)	$	(4	)	$	(6	)	$	1	$	(9	)


(a)	Relates to Discovery, an unconsolidated affiliate.

Schedule of Changes in Derivative Instruments Not Designated as Hedging Instruments



Commodity Derivatives: Statements of Operations Line Item		Year Ended December 31,
		2018			2017			2016
	(millions)
Realized (losses) gains		$	(149	)	$	(12	)	$	116
Unrealized gains (losses)		108			(28		)	(139		)
Trading and marketing losses, net		$	(41	)	$	(40	)	$	(23	)

Schedule of Net Long or Short Positions Expected to be Realized



	December 31, 2018
	Crude Oil		Natural Gas		Natural Gas Liquids		Natural Gas Basis Swaps
Year of Expiration	Net Short Position (Bbls)		Net Short Position (MMBtu)		Net Short Position (Bbls)		Net (Short) Long Position (MMBtu)
2019	(1,619,000	)	(40,291,250	)	(36,312,499	)	(2,165,000	)
2020	(204,000	)	—		(13,862,378	)	3,660,000
2021	—		—		(5,755,322	)	(3,650,000	)

	December 31, 2017
	Crude Oil		Natural Gas		Natural Gas Liquids		Natural Gas Basis Swaps
Year of Expiration	Net Short Position (Bbls)		Net Short Position (MMBtu)		Net (Short) Long Position (Bbls)		Net Long Position (MMBtu)
2018	(2,701,000	)	(35,977,400	)	(19,656,392	)	3,202,500
2019	(631,000	)	—		(2,357,156	)	7,177,500
2020	(50,000	)	—		238,548		3,660,000

Partnership Equity and Distributions (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Cash Distribution

Distributions — The following table presents our cash distributions paid in 2018, 2017 and 2016:



Payment Date	Per Unit Distribution		Total Cash Distribution
			(millions)
Distributions to common unitholders
November 14, 2018	$	0.7800	$	155
August 14, 2018	$	0.7800	$	154
May 15, 2018	$	0.7800	$	155
February 14, 2018	$	0.7800	$	194
November 14, 2017	$	0.7800	$	155
August 14, 2017	$	0.7800	$	134
May 15, 2017	$	0.7800	$	135
February 14, 2017	$	0.7800	$	121
November 14, 2016	$	0.7800	$	120
August 12, 2016	$	0.7800	$	121
May 13, 2016	$	0.7800	$	121
February 12, 2016	$	0.7800	$	121

Distributions to Series A Preferred unitholders
December 17, 2018	$	36.8750	$	18
June 15, 2018	$	41.9965	$	21

Distributions to Series B Preferred unitholders
December 17, 2018	$	0.4922	$	3
September 17, 2018	$	0.6781	$	4

Equity-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Fair Value of Unvested Awards

The following table presents the fair value of unvested unit-based awards related to the strategic performance units and phantom units:



	Vesting Period (years)	Unrecognized Compensation Expense at December 31, 2018 (millions)		Estimated Forfeiture Rate	Weighted-Average Remaining Vesting (years)
DCP Midstream LTIP:
SPUs	3	$	4	0%-11%	2
Phantom Units	1-3	$	4	0%-11%	2

Schedule of Nonvested Share Activity



	Units		Grant Date Weighted-Average Price Per Unit		Measurement Date Weighted-Average Price Per Unit
Outstanding at January 1, 2016	208,459		$	48.46
Granted	131,610		$	45.31
Forfeited	(8,463	)	$	46.27
Vested (a)	(98,295	)	$	54.05
Outstanding at December 31, 2016	233,311		$	44.41
Granted	98,628		$	76.38
Forfeited	(18,577	)	$	50.31
Vested (b)	(98,627	)	$	58.80
Outstanding at December 31, 2017	214,735		$	51.98
Granted	168,160		$	36.23
Forfeited	(10,933	)	$	47.79
Vested (c)	(120,643	)	$	48.41
Outstanding at December 31, 2018	251,319		$	43.33	$	34.30
Expected to vest	231,936		$	43.54	$	34.53

(a) The 2014 grants vested at 130%.

(b) The 2015 grants vested at 180%.

Phantom Units - The DERs are paid quarterly in arrears. The following table presents information related to Phantom Units:



	Units		Grant Date Weighted-Average Price Per Unit		Measurement Date Weighted-Average Price Per Unit
Outstanding at January 1, 2016	204,368		$	49.85
Granted	132,870		$	45.33
Forfeited	(3,240	)	$	48.62
Vested	(126,681	)	$	50.13
Outstanding at December 31, 2016	207,317		$	46.80
Granted	180,337		$	59.43
Forfeited	(16,677	)	$	51.73
Vested	(169,896	)	$	53.35
Outstanding at December 31, 2017	201,081		$	52.18
Granted	242,780		$	36.87
Forfeited	(17,696	)	$	45.35
Vested	(194,459	)	$	45.16
Outstanding at December 31, 2018	231,706		$	42.55	$	33.08
Expected to vest	215,482		$	42.52	$	33.06

Share-based Compensation Arrangements by Share-based Payment Award, Performance-Based Units, Vested and Expected to Vest [Table Text Block]

The following table presents the fair value of units vested and the unit-based liabilities paid for unit based awards related to the phantom units:



	Units	Fair Value of Units Vested		Unit-Based Liabilities Paid
		(millions)
Vested or paid in cash in 2016	126,681	$	4	$	5
Vested or paid in cash in 2017	169,896	$	7	$	4
Vested or paid in cash in 2018	194,459	$	5	$	7

The following table presents the fair value of units vested and the unit-based liabilities paid for unit-based awards related to the strategic performance units:



	Units	Fair Value of Units Vested		Unit-Based Liabilities Paid
		(millions)
Vested or paid in cash in 2016	98,295	$	7	$	4
Vested or paid in cash in 2017	98,627	$	11	$	7
Vested or paid in cash in 2018	120,643	$	9	$	11

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Income Tax Expense

Income tax expense consists of the following:



	Year Ended December 31,
	2018			2017			2016
	(millions)
Current:
Federal income tax expense	$	—		$	—		$	(19	)
State income tax expense	—			(1		)	(2		)
Deferred:
Federal income tax expense	—			—			(22		)
State income tax expense	(3		)	(1		)	(3		)
Total income tax expense	$	(3	)	$	(2	)	$	(46	)

Business Segments (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Segment Information

Year Ended December 31, 2018:



	Logistics and Marketing			Gathering and Processing			Other			Eliminations			Total
	(millions)
Total operating revenue	$	9,014		$	5,843		$	—		$	(5,035	)	$	9,822
Gross margin (a)	$	225		$	1,578		$	—		$	—		$	1,803
Operating and maintenance expense	(47		)	(692		)	(21		)	—			(760		)
Depreciation and amortization expense	(15		)	(346		)	(27		)	—			(388		)
General and administrative expense	(12		)	(19		)	(245		)	—			(276		)
Asset impairments	—			(145		)	—			—			(145		)
Other expense, net	(4		)	(6		)	(1		)	—			(11		)
Loss from financing activities	—			—			(19		)	—			(19		)
Earnings from unconsolidated affiliates	362			8			—			—			370
Interest expense	—			—			(269		)	—			(269		)
Income tax expense	—			—			(3		)	—			(3		)
Net income (loss)	$	509		$	378		$	(585	)	$	—		$	302
Net income attributable to noncontrolling interests	—			(4		)	—			—			(4		)
Net income (loss) attributable to partners	$	509		$	374		$	(585	)	$	—		$	298
Non-cash derivative mark-to-market (b)	$	(4	)	$	112		$	—		$	—		$	108
Capital expenditures	$	8		$	570		$	17		$	—		$	595
Investments in unconsolidated affiliates, net	$	350		$	4		$	—		$	—		$	354

Year Ended December 31, 2017:



	Logistics and Marketing			Gathering and Processing			Other			Eliminations			Total
	(millions)
Total operating revenue	$	7,757		$	5,467		$	—		$	(4,762	)	$	8,462
Gross margin (a)	$	200		$	1,377		$	—		$	—		$	1,577
Operating and maintenance expense	(41		)	(602		)	(18		)	—			(661		)
Depreciation and amortization expense	(14		)	(343		)	(22		)	—			(379		)
General and administrative expense	(11		)	(19		)	(260		)	—			(290		)
Asset impairments	—			(48		)	—			—			(48		)
Other expense	(11		)	—			—			—			(11		)
Gain on sale of assets, net	—			34			—			—			34
Earnings from unconsolidated affiliates	243			60			—			—			303
Interest expense	—			—			(289		)	—			(289		)
Income tax expense	—			—			(2		)	—			(2		)
Net income (loss)	$	366		$	459		$	(591	)	$	—		$	234
Net income attributable to noncontrolling interests	—			(5		)	—			—			(5		)
Net income (loss) attributable to partners	$	366		$	454		$	(591	)	$	—		$	229
Non-cash derivative mark-to-market (b)	$	(4	)	$	(24	)	$	—		$	—		$	(28	)
Non-cash lower of cost or market adjustments	$	2		$	—		$	—		$	—		$	2
Capital expenditures	$	3		$	350		$	22		$	—		$	375
Investments in unconsolidated affiliates, net	$	147		$	1		$	—		$	—		$	148

Year Ended December 31, 2016:



	Logistics and Marketing			Gathering and Processing			Other			Eliminations			Total
	(millions)
Total operating revenue	$	6,186		$	4,490		$	—		$	(3,783	)	$	6,893
Gross margin (a)	$	205		$	1,227		$	—		$	—		$	1,432
Operating and maintenance expense	(43		)	(611		)	(16		)	—			(670		)
Depreciation and amortization expense	(15		)	(344		)	(19		)	—			(378		)
General and administrative expense	(9		)	(14		)	(269		)	—			(292		)
Other (expense) income	(5		)	73			(3		)	—			65
Gain on sale of assets, net	16			19			—			—			35
Restructuring costs	—			—			(13		)	—			(13		)
Earnings from unconsolidated affiliates	209			73			—			—			282
Interest expense	—			—			(321		)	—			(321		)
Income tax expense	—			—			(46		)	—			(46		)
Net income (loss)	$	358		$	423		$	(687	)	$	—		$	94
Net income attributable to noncontrolling interests	—			(6		)	—			—			(6		)
Net income (loss) attributable to partners	$	358		$	417		$	(687	)	$	—		$	88
Non-cash derivative mark-to-market (b)	$	(20	)	$	(119	)	$	—		$	—		$	(139	)
Non-cash lower of cost or market adjustments	$	3		$	—		$	—		$	—		$	3
Capital expenditures	$	10		$	107		$	27		$	—		$	144
Investments in unconsolidated affiliates, net	$	52		$	1		$	—		$	—		$	53



	December 31,		December 31,
	2018		2017
	(millions)
Segment long-term assets:
Gathering and Processing	$	9,058	$	8,943
Logistics and Marketing	3,661		3,348
Other (c)	276		265
Total long-term assets	12,995		12,556
Current assets	1,271		1,322
Total assets	$	14,266	$	13,878

(a)


(b)	Non-cash commodity derivative mark-to-market is included in gross margin, along with cash settlements for our commodity derivative contracts.


(c)	Other long-term assets not allocable to segments consist of corporate leasehold improvements and other long-term assets.

Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Data (Unaudited) [Abstract]

Quarterly Financial Information (Unaudited) [Table Text Block]

Our consolidated results of operations by quarter for the years ended December 31, 2018 and 2017 were as follows:



2018	First			Second			Third			Fourth			Year ended December 31, 2018
	(millions, except per unit amounts)
Total operating revenues	$	2,139		$	2,317		$	2,759		$	2,607		$	9,822
Operating income	$	53		$	34		$	66		$	70		$	223
Net income	$	63		$	62		$	82		$	95		$	302
Net income attributable to noncontrolling interests	$	(1	)	$	(1	)	$	(1	)	$	(1	)	$	(4	)
Net income attributable to partners	$	62		$	61		$	81		$	94		$	298
Net income allocable to limited partners	$	12		$	10		$	26		$	39		$	87
Basic and diluted net income per limited partner unit	$	0.08		$	0.07		$	0.18		$	0.28		$	0.61



2017	First		Second			Third			Fourth			Year Ended December 31, 2017
	(millions, except per unit amounts)
Total operating revenues	$	2,121	$	1,949		$	2,055		$	2,337		$	8,462
Operating income (loss)	$	101	$	78		$	(19	)	$	62		$	222
Net income (loss)	$	101	$	89		$	(20	)	$	64		$	234
Net income attributable to noncontrolling interests	$	—	$	(1	)	$	—		$	(4	)	$	(5	)
Net income (loss) attributable to partners	$	101	$	88		$	(20	)	$	60		$	229
Net income allocable to limited partners	$	59	$	47		$	(59	)	$	14		$	61
Basic and diluted net income per limited partner unit	$	0.41	$	0.33		$	(0.41	)	$	0.10		$	0.43

Condensed Consolidating Financial Information (Tables)

12 Months Ended

Dec. 31, 2018

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Condensed Consolidating Balance Sheets



	Condensed Consolidating Balance Sheets
	December 31, 2018
	Parent Guarantor		Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
ASSETS
Current assets:
Cash and cash equivalents	$	—	$	—		$	1		$	—		$	1
Accounts receivable, net	—		—			1,033			—			1,033
Inventories	—		—			79			—			79
Other	—		—			158			—			158
Total current assets	—		—			1,271			—			1,271
Property, plant and equipment, net	—		—			9,135			—			9,135
Goodwill and intangible assets, net	—		—			328			—			328
Advances receivable — consolidated subsidiaries	2,452		1,883			—			(4,335		)	—
Investments in consolidated subsidiaries	4,818		8,113			—			(12,931		)	—
Investments in unconsolidated affiliates	—		—			3,340			—			3,340
Other long-term assets	—		—			192			—			192
Total assets	$	7,270	$	9,996		$	14,266		$	(17,266	)	$	14,266
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	$	2	$	71		$	1,306		$	—		$	1,379
Current maturities of long-term debt	—		325			200			—			525
Advances payable — consolidated subsidiaries	—		—			4,335			(4,335		)	—
Long-term debt	—		4,782			—			—			4,782
Other long-term liabilities	—		—			283			—			283
Total liabilities	2		5,178			6,124			(4,335		)	6,969
Commitments and contingent liabilities
Equity:
Partners’ equity:
Net equity	7,268		4,821			8,118			(12,931		)	7,276
Accumulated other comprehensive loss	—		(3		)	(5		)	—			(8		)
Total partners’ equity	7,268		4,818			8,113			(12,931		)	7,268
Noncontrolling interests	—		—			29			—			29
Total equity	7,268		4,818			8,142			(12,931		)	7,297
Total liabilities and equity	$	7,270	$	9,996		$	14,266		$	(17,266	)	$	14,266



	Condensed Consolidating Balance Sheets
	December 31, 2017
	Parent Guarantor		Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
ASSETS
Current assets:
Cash and cash equivalents	$	—	$	155		$	1		$	—		$	156
Accounts receivable, net	—		—			981			—			981
Inventories	—		—			68			—			68
Other	—		—			117			—			117
Total current assets	—		155			1,167			—			1,322
Property, plant and equipment, net	—		—			8,983			—			8,983
Goodwill and intangible assets, net	—		—			337			—			337
Advances receivable — consolidated subsidiaries	2,895		1,614			—			(4,509		)	—
Investments in consolidated subsidiaries	4,513		7,522			—			(12,035		)	—
Investments in unconsolidated affiliates	—		—			3,050			—			3,050
Other long-term assets	—		—			186			—			186
Total assets	$	7,408	$	9,291		$	13,723		$	(16,544	)	$	13,878
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	$	—	$	71		$	1,417		$	—		$	1,488
Advances payable — consolidated subsidiaries	—		—			4,509			(4,509		)	—
Long-term debt	—		4,707			—			—			4,707
Other long-term liabilities	—		—			245			—			245
Total liabilities	—		4,778			6,171			(4,509		)	6,440
Commitments and contingent liabilities
Equity:
Partners’ equity:
Net equity	7,408		4,517			7,527			(12,035		)	7,417
Accumulated other comprehensive loss	—		(4		)	(5		)	—			(9		)
Total partners’ equity	7,408		4,513			7,522			(12,035		)	7,408
Noncontrolling interests	—		—			30			—			30
Total equity	7,408		4,513			7,552			(12,035		)	7,438
Total liabilities and equity	$	7,408	$	9,291		$	13,723		$	(16,544	)	$	13,878

Condensed Income Statement



	Condensed Consolidating Statement of Operations
	Year Ended December 31, 2016
	Parent Guarantor		Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Operating revenues:
Sales of natural gas, NGLs and condensate	$	—	$	—		$	6,269		$	—		$	6,269
Transportation, processing and other	—		—			647			—			647
Trading and marketing losses, net	—		—			(23		)	—			(23		)
Total operating revenues	—		—			6,893			—			6,893
Operating costs and expenses:
Purchases and related costs	—		—			5,461			—			5,461
Operating and maintenance expense	—		—			670			—			670
Depreciation and amortization expense	—		—			378			—			378
General and administrative expense	—		—			292			—			292
Gain on sale of assets, net	—		—			(35		)	—			(35		)
Restructuring costs	—		—			13			—			13
Other income, net	—		—			(65		)	—			(65		)
Total operating costs and expenses	—		—			6,714			—			6,714
Operating income	—		—			179			—			179
Interest expense, net	—		(321		)	—			—			(321		)
Income from consolidated subsidiaries	88		409			—			(497		)	—
Earnings from unconsolidated affiliates	—		—			282			—			282
Income before income taxes	88		88			461			(497		)	140
Income tax expense	—		—			(46		)	—			(46		)
Net income	88		88			415			(497		)	94
Net income attributable to noncontrolling interests	—		—			(6		)	—			(6		)
Net income attributable to partners	$	88	$	88		$	409		$	(497	)	$	88



	Condensed Consolidating Statement of Operations
	Year Ended December 31, 2018
	Parent Guarantor		Subsidiary Issuer			Non- Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Operating revenues:
Sales of natural gas, NGLs and condensate	$	—	$	—		$	9,374		$	—		$	9,374
Transportation, processing and other	—		—			489			—			489
Trading and marketing losses, net	—		—			(41		)	—			(41		)
Total operating revenues	—		—			9,822			—			9,822
Operating costs and expenses:
Purchases and related costs	—		—			8,019			—			8,019
Operating and maintenance expense	—		—			760			—			760
Depreciation and amortization expense	—		—			388			—			388
General and administrative expense	—		—			276			—			276
Asset impairments	—		—			145			—			145
Other expense, net	—		—			11			—			11
Total operating costs and expenses	—		—			9,599			—			9,599
Operating income	—		—			223			—			223
Loss from financing activities	—		(19		)	—			—			(19		)
Interest expense, net	—		(268		)	(1		)	—			(269		)
Income from consolidated subsidiaries	298		585			—			(883		)	—
Earnings from unconsolidated affiliates	—		—			370			—			370
Income before income taxes	298		298			592			(883		)	305
Income tax expense	—		—			(3		)	—			(3		)
Net income	298		298			589			(883		)	302
Net income attributable to noncontrolling interests	—		—			(4		)	—			(4		)
Net income attributable to partners	$	298	$	298		$	585		$	(883	)	$	298



	Condensed Consolidating Statement of Operations
	Year Ended December 31, 2017
	Parent Guarantor		Subsidiary Issuer			Non- Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Operating revenues:
Sales of natural gas, NGLs and condensate	$	—	$	—		$	7,850		$	—		$	7,850
Transportation, processing and other	—		—			652			—			652
Trading and marketing losses, net	—		—			(40		)	—			(40		)
Total operating revenues	—		—			8,462			—			8,462
Operating costs and expenses:
Purchases and related costs	—		—			6,885			—			6,885
Operating and maintenance expense	—		—			661			—			661
Depreciation and amortization expense	—		—			379			—			379
General and administrative expense	—		—			290			—			290
Asset impairments	—		—			48			—			48
Gain on sale of assets, net	—		—			(34		)	—			(34		)
Other expense, net	—		—			11			—			11
Total operating costs and expenses	—		—			8,240			—			8,240
Operating income	—		—			222			—			222
Interest expense, net	—		(289		)	—			—			(289		)
Income from consolidated subsidiaries	229		518			—			(747		)	—
Earnings from unconsolidated affiliates	—		—			303			—			303
Income before income taxes	229		229			525			(747		)	236
Income tax expense	—		—			(2		)	—			(2		)
Net income	229		229			523			(747		)	234
Net income attributable to noncontrolling interests	—		—			(5		)	—			(5		)
Net income attributable to partners	$	229	$	229		$	518		$	(747	)	$	229

Condensed Statement of Comprehensive Income



	Condensed Consolidating Statement of Comprehensive Income
	Year Ended December 31, 2016
	Parent Guarantor		Subsidiary Issuer		Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Net income	$	88	$	88	$	415		$	(497	)	$	94
Other comprehensive income:
Total other comprehensive income	—		—		—			—			—
Total comprehensive income	88		88		415			(497		)	94
Total comprehensive income attributable to noncontrolling interests	—		—		(6		)	—			(6		)
Total comprehensive income attributable to partners	$	88	$	88	$	409		$	(497	)	$	88



	Condensed Consolidating Statement of Comprehensive Income
	Year Ended December 31, 2018
	Parent Guarantor		Subsidiary Issuer		Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Net income	$	298	$	298	$	589		$	(883	)	$	302
Other comprehensive income:
Reclassification of cash flow hedge losses into earnings	—		1		—			—			1
Other comprehensive income from consolidated subsidiaries	1		—		—			(1		)	—
Total other comprehensive income	1		1		—			(1		)	1
Total comprehensive income	299		299		589			(884		)	303
Total comprehensive income attributable to noncontrolling interests	—		—		(4		)	—			(4		)
Total comprehensive income attributable to partners	$	299	$	299	$	585		$	(884	)	$	299



	Condensed Consolidating Statement of Comprehensive Income
	Year Ended December 31, 2017
	Parent Guarantor		Subsidiary Issuer		Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
Net income	$	229	$	229	$	523		$	(747	)	$	234
Other comprehensive income:
Reclassification of cash flow hedge losses into earnings	—		1		—			—			1
Other comprehensive income from consolidated subsidiaries	1		—		—			(1		)	—
Total other comprehensive income	1		1		—			(1		)	1
Total comprehensive income	230		230		523			(748		)	235
Total comprehensive income attributable to noncontrolling interests	—		—		(5		)	—			(5		)
Total comprehensive income attributable to partners	$	230	$	230	$	518		$	(748	)	$	230

Condensed Consolidating Statements of Cash Flows



	Condensed Consolidating Statement of Cash Flows
	Year Ended December 31, 2018
	Parent Guarantor			Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$	—		$	(263	)	$	925		$	—		$	662
INVESTING ACTIVITIES:
Intercompany transfers	443			(269		)	—			(174		)	—
Capital expenditures	—			—			(595		)	—			(595		)
Investments in unconsolidated affiliates, net	—			—			(354		)	—			(354		)
Proceeds from sale of assets	—			—			4			—			4
Net cash provided by (used in) investing activities	443			(269		)	(945		)	(174		)	(945		)
FINANCING ACTIVITIES:
Intercompany transfers	—			—			(174		)	174			—
Proceeds from debt	—			4,961			200			—			5,161
Payments of debt	—			(4,560		)	—			—			(4,560		)
Costs incurred to redeem senior notes	—			(18		)	—			—			(18		)
Proceeds from issuance of preferred limited partner units, net of offering costs	261			—			—			—			261
Distributions to preferred limited partners	(46		)	—			—			—			(46		)
Distributions to limited partners and general partner	(658		)	—			—			—			(658		)
Distributions to noncontrolling interests	—			—			(5		)	—			(5		)
Other	—			(6		)	(1		)	—			(7		)
Net cash (used in) provided by financing activities	(443		)	377			20			174			128
Net change in cash and cash equivalents	—			(155		)	—			—			(155		)
Cash and cash equivalents, beginning of period	—			155			1			—			156
Cash and cash equivalents, end of period	$	—		$	—		$	1		$	—		$	1



	Condensed Consolidating Statements of Cash Flows
	Year Ended December 31, 2017
	Parent Guarantor			Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$	—		$	(283	)	$	1,179		$	—		$	896
INVESTING ACTIVITIES:
Intercompany transfers	58			1,141			—			(1,199		)	—
Capital expenditures	—			—			(375		)	—			(375		)
Investments in unconsolidated affiliates, net	—			—			(148		)	—			(148		)
Proceeds from sale of assets	—			—			132			—			132
Net cash provided by (used in) investing activities	58			1,141			(391		)	(1,199		)	(391		)
FINANCING ACTIVITIES:
Intercompany transfers	—			—			(1,199		)	1,199			—
Proceeds from long-term debt	—			116			—			—			116
Payments of debt	—			(811		)	—			—			(811		)
Proceeds from issuance of preferred limited partner units, net of offering costs	487			—			—			—			487
Net change in advances to predecessor from DCP Midstream, LLC	—			—			418			—			418
Distributions to limited partners and general partner	(545		)	—			—			—			(545		)
Distributions to noncontrolling interests	—			—			(7		)	—			(7		)
Other	—			(8		)	—			—			(8		)
Net cash used in financing activities	(58		)	(703		)	(788		)	1,199			(350		)
Net change in cash and cash equivalents	—			155			—			—			155
Cash and cash equivalents, beginning of period	—			—			1			—			1
Cash and cash equivalents, end of period	$	—		$	155		$	1		$	—		$	156



	Condensed Consolidating Statements of Cash Flows
	Year Ended December 31, 2016
	Parent Guarantor			Subsidiary Issuer			Non-Guarantor Subsidiaries			Consolidating Adjustments			Consolidated
	(millions)
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$	—		$	(305	)	$	950		$	—		$	645
INVESTING ACTIVITIES:
Intercompany transfers	483			585			—			(1,068		)	—
Capital expenditures	—			—			(144		)	—			(144		)
Investments in unconsolidated affiliates, net	—			—			(53		)	—			(53		)
Proceeds from sale of assets	—			—			163			—			163
Net cash (used in) provided by investing activities	483			585			(34		)	(1,068		)	(34		)
FINANCING ACTIVITIES:
Intercompany transfers	—			—			(1,068		)	1,068			—
Proceeds from long-term debt	—			3,353			—			—			3,353
Payments of long-term debt	—			(3,628		)	—			—			(3,628		)
Net change in advances to predecessor from DCP Midstream, LLC	—			—			157			—			157
Distributions to limited partners and general partner	(483		)	—			—			—			(483		)
Distributions to noncontrolling interests	—			—			(7		)	—			(7		)
Other	—			(5		)	—			—			(5		)
Net cash provided by (used in) financing activities	(483		)	(280		)	(918		)	1,068			(613		)
Net change in cash and cash equivalents	—			—			(2		)	—			(2		)
Cash and cash equivalents, beginning of year	—			—			3			—			3
Cash and cash equivalents, end of year	$	—		$	—		$	1		$	—		$	1

Description of Business and Basis of Presentation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018
Investments in Greater Than 20%
Business Acquisition [Line Items]
Equity method ownership investment (as percent)	20.00%
Investments in Less Than 20%
Business Acquisition [Line Items]
Equity method ownership investment (as percent)	20.00%
DCP Midstream, LLC \| DCP Midstream GP, LLC
Business Acquisition [Line Items]
Ownership interest percentage by parent	100.00%
DCP Midstream, LLC \| DCP Midstream LP
Business Acquisition [Line Items]
Ownership interest percentage by parent	38.10%
Phillips 66 \| DCP Midstream, LLC
Business Acquisition [Line Items]
Ownership interest percentage by parent	50.00%
Enbridge \| DCP Midstream, LLC
Business Acquisition [Line Items]
Ownership interest percentage by parent	50.00%

Revenue Impact of Adoption (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Item Effected [Line Items]
Sales Revenue, Goods, Net									$ 9,374	$ 7,850	$ 6,269
Transportation, processing and other									489	652	647
Purchases and related costs									8,019	6,885	5,461
Net income	$ 95	$ 82	$ 62	$ 63	$ 64	$ (20)	$ 89	$ 101	302	234	94
Third Party
Item Effected [Line Items]
Sales Revenue, Goods, Net									7,764	6,576	5,317
Purchases and related costs									7,123	$ 6,308	$ 4,978
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Item Effected [Line Items]
Transportation, processing and other									165
Net income									0
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Third Party
Item Effected [Line Items]
Sales Revenue, Goods, Net									148
Purchases and related costs									313
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Item Effected [Line Items]
Transportation, processing and other									654
Net income									302
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Third Party
Item Effected [Line Items]
Sales Revenue, Goods, Net									7,912
Purchases and related costs									$ 7,436

Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
Revenue Recognition (Details) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									$ 9,374	$ 7,850	$ 6,269
Transportation, processing and other									489	652	647
Trading and marketing losses, net									(41)	(40)	(23)
Total operating revenues	$ 2,607	$ 2,759	$ 2,317	$ 2,139	$ 2,337	$ 2,055	$ 1,949	$ 2,121	9,822	8,462	6,893
Revenue, Remaining Performance Obligation	$ 219								219
Revenue from contract with customer not within the scope of Topic 606									4,347
Natural Gas
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									2,528
NGLs and Condensate [Member]
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									6,846
Logistics and Marketing
Disaggregation of Revenue [Line Items]
Transportation, processing and other									57
Trading and marketing losses, net									(60)
Total operating revenues									9,014
Logistics and Marketing \| Natural Gas
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									2,325
Logistics and Marketing \| NGLs and Condensate [Member]
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									6,692
Eliminations
Disaggregation of Revenue [Line Items]
Transportation, processing and other									0
Trading and marketing losses, net									0
Total operating revenues									(5,035)
Eliminations \| Natural Gas
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									(1,752)
Eliminations \| NGLs and Condensate [Member]
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									(3,283)
Gathering and Processing
Disaggregation of Revenue [Line Items]
Transportation, processing and other									432
Trading and marketing losses, net									19
Total operating revenues									5,843
Gathering and Processing \| Natural Gas
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									1,955
Gathering and Processing \| NGLs and Condensate [Member]
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									3,437
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Transportation, processing and other									165
Third Party
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									7,764	$ 6,576	$ 5,317
Third Party \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Sales of natural gas, NGLs and condensate									$ 148

Contract Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
Contract Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Contract Assets and Liabilities [Abstract]
Contract with Customer, Liability	$ 34		$ 0
Cumulative effect of implementation of Topic 606		$ 36
Contract with Customer, Liability, Revenue Recognized	$ (2)
Revenue, Performance Obligation, Recognition Period in Years	35 years

Agreements and Transactions with Affiliates - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Expense
Related Party Transaction [Line Items]
Labor and related expense	$ 209	$ 197	$ 206
General and Administrative Expense
Related Party Transaction [Line Items]
Labor and related expense	$ 187	$ 182	$ 197

Agreements and Transactions with Affiliates - Transactions with Affiliates (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Sales of natural gas, NGLs and condensate	$ 9,374	$ 7,850	$ 6,269
Transportation, processing and other	489	652	647
Purchases and related costs	8,019	6,885	5,461
Operating and maintenance expense	760	661	670
Affiliated Entity \| Unconsolidated Affiliates
Related Party Transaction [Line Items]
Sales of natural gas, NGLs and condensate	65	54	43
Transportation, processing and other	6	5	5
Purchases and related costs	723	504	432
Affiliated Entity \| Phillips 66
Related Party Transaction [Line Items]
Sales of natural gas, NGLs and condensate	1,534	1,172	909
Purchases and related costs	138	30	18
Operating and maintenance expense	13	2	2
Affiliated Entity \| Enbridge
Related Party Transaction [Line Items]
Sales of natural gas, NGLs and condensate	11	48	0
Purchases and related costs	35	43	33
Operating and maintenance expense	$ 0	$ 2	$ 4

Agreements and Transactions with Affiliates - Balances with Affiliates (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Accounts receivable	$ 166	$ 191
Accounts payable	96	68
Unconsolidated Affiliates
Related Party Transaction [Line Items]
Accounts receivable	21	24
Accounts payable	72	53
Other assets	0	4
Phillips 66
Related Party Transaction [Line Items]
Accounts receivable	145	156
Accounts payable	22	6
Other assets	0	0
Enbridge
Related Party Transaction [Line Items]
Accounts receivable	0	11
Accounts payable	$ 2	$ 9

Inventories - Schedule of Inventories (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Components Of Inventory [Line Items]
Total inventories	$ 79	$ 68
Natural Gas
Components Of Inventory [Line Items]
Total inventories	34	30
Natural Gas Liquids
Components Of Inventory [Line Items]
Total inventories	$ 45	$ 38

Inventories - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Lower of cost or market adjustment	$ 0	$ 2	$ 3

Property, Plant and Equipment - Classification of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 14,724	$ 14,532
Accumulated depreciation	(5,589)	(5,549)
Property, plant and equipment, net	9,135	8,983
Gathering and transmission systems
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 8,492	8,473
Gathering and transmission systems \| Minimum
Property, Plant and Equipment [Line Items]
Depreciable life of property, plant and equipment	20 years
Gathering and transmission systems \| Maximum
Property, Plant and Equipment [Line Items]
Depreciable life of property, plant and equipment	50 years
Processing, storage and terminal facilities
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 5,194	5,128
Processing, storage and terminal facilities \| Minimum
Property, Plant and Equipment [Line Items]
Depreciable life of property, plant and equipment	35 years
Processing, storage and terminal facilities \| Maximum
Property, Plant and Equipment [Line Items]
Depreciable life of property, plant and equipment	60 years
Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 568	557
Other \| Minimum
Property, Plant and Equipment [Line Items]
Depreciable life of property, plant and equipment	3 years
Other \| Maximum
Property, Plant and Equipment [Line Items]
Depreciable life of property, plant and equipment	30 years
Construction work in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 470	$ 374

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Interest capitalized on construction projects	$ 19	$ 7	$ 1
Depreciation expense	$ 378	$ 367	$ 366

Property, Plant and Equipment Property, Plant and Equipment - Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment - Asset Retirement Obligations [Abstract]
Asset Retirement Obligation	$ 140	$ 126	$ 124
Accretion Expense	8	8	$ 7
Asset Retirement Obligation, Revision of Estimate	$ 6	$ (6)

Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
Goodwill (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Dispositions	$ 0	$ 5
Balance, end of period	231	231	$ 236
Gathering and Processing
Goodwill [Line Items]
Dispositions	0	5
Balance, end of period	159	159	164
Logistics and Marketing
Goodwill [Line Items]
Dispositions	0	0
Balance, end of period	$ 72	$ 72	$ 72
Wholesale Propane Logistics [Member]
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	10.00%
Balance, end of period	$ 37

Goodwill and Intangible Assets - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	$ 410	$ 410
Accumulated amortization	(170)	(161)
Accumulated impairment	(143)	(143)
Intangible assets, net	97	106
Amortization expense	$ 9	$ 10	$ 12
Weighted Average
Finite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	12 years
Minimum
Finite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	3 years
Maximum
Finite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	17 years

Goodwill and Intangible Assets - Finite-Lived Intangible Assets, Future Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
2017	$ 9
2018	9
2019	9
2020	9
2021	8
Thereafter	53
Intangible assets, net	$ 97	$ 106
Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	3 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	17 years
Weighted Average
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	12 years

Investments In Unconsolidated Affiliates - Investments In Unconsolidated Affiliates (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 3,340	$ 3,050
DCP Sand Hills Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 634	648
Equity method ownership investment (as percent)	66.67%
Investments in unconsolidated affiliates	$ 1,791	1,633
DCP Southern Hills Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 142	145
Equity method ownership investment (as percent)	66.67%
Investments in unconsolidated affiliates	$ 728	739
Discovery Producer Services LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ (15)	(18)
Equity method ownership investment (as percent)	40.00%
Investments in unconsolidated affiliates	$ 344	362
Front Range Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 4	4
Equity method ownership investment (as percent)	33.33%
Investments in unconsolidated affiliates	$ 175	165
Texas Express Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 3	3
Equity method ownership investment (as percent)	10.00%
Investments in unconsolidated affiliates	$ 95	90
Panola Pipeline Company, LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	15.00%
Investments in unconsolidated affiliates	$ 23	24
Mont Belvieu Enterprise Fractionator
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	12.50%
Investments in unconsolidated affiliates	$ 24	23
Gulf Coast Express [Member]
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	25.00%
Investments in unconsolidated affiliates	$ 146	0
Mont Belvieu 1 Fractionator
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 0	(1)
Equity method ownership investment (as percent)	20.00%
Investments in unconsolidated affiliates	$ 10	10
Other
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 4	$ 4

Investments in Unconsolidated Affiliates - Earnings from Investments in Unconsolidated Affiliates (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	$ 370	$ 303	$ 282
DCP Sand Hills Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	223	148	110
DCP Southern Hills Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	68	47	44
Discovery Producer Services LLC
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	8	61	73
Front Range Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	24	17	19
Texas Express Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	19	9	9
Mont Belvieu Enterprise Fractionator
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	10	13	16
Mont Belvieu 1 Fractionator
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	16	6	9
Other
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated affiliates	$ 2	$ 2	$ 2

Investments in Unconsolidated Affiliates - Equity Method Investment Summarized Financial Information, Statement of Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Operating revenue	$ 1,560	$ 1,397	$ 1,311
Operating expenses	613	647	539
Net income	$ 945	$ 747	$ 768

Investments in Unconsolidated Affiliates - Equity Method Investment Summarized Financial Information, Balance Sheet (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Current assets	$ 411	$ 244
Long-term assets	6,359	5,319
Current liabilities	(424)	(196)
Long-term liabilities	(221)	(200)
Net assets	$ 6,125	$ 5,167

Fair Value Measurement - Financial Instruments Carried at Fair Value (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	$ 0	$ 156
Current Assets \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	108	30
Long- Term Assets \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	8	3
Current Liabilities \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	(91)	(76)
Long- Term Liabilities \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	(8)	(15)
Level 1 \| Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	0	156
Level 1 \| Current Assets \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	62	10
Level 1 \| Long- Term Assets \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	4	1
Level 1 \| Current Liabilities \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	(39)	(29)
Level 1 \| Long- Term Liabilities \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	(1)	(3)
Level 2 \| Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	0	0
Level 2 \| Current Assets \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	32	17
Level 2 \| Long- Term Assets \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	2	1
Level 2 \| Current Liabilities \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	(52)	(34)
Level 2 \| Long- Term Liabilities \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	(5)	(11)
Level 3 \| Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	0	0
Level 3 \| Current Assets \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	14	3
Level 3 \| Long- Term Assets \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	2	1
Level 3 \| Current Liabilities \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	0	(13)
Level 3 \| Long- Term Liabilities \| Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivatives	$ (2)	$ 1

Fair Value Measurement - Condensed Consolidated Balance Sheets for Derivative Financial Instruments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 3	$ 9
Net realized and unrealized gains (losses) included in earnings	14	14
Transfers out of Level 3		0
Settlements	(3)	(13)
Ending balance	14	3
Net unrealized gains (losses) on derivatives still held included in earnings	14	3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Assets, CME Rule 814 adjustments		(7)
Long- Term Assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1	5
Net realized and unrealized gains (losses) included in earnings	1	1
Transfers out of Level 3		0
Settlements	0	0
Ending balance	2	1
Net unrealized gains (losses) on derivatives still held included in earnings	1	(4)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Assets, CME Rule 814 adjustments		(5)
Current Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	(13)	(23)
Net realized and unrealized (losses) gains included in earnings	(6)	(44)
Transfers out of Level 3		0
Settlements	19	36
Ending balance	0	(13)
Net unrealized gains (losses) on derivatives still held included in earnings	0	(13)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liabilities, CME Rule 814 adjustments		(18)
Long- Term Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	(1)	0
Net realized and unrealized (losses) gains included in earnings	(1)	(3)
Transfers out of Level 3		2
Settlements	0	0
Ending balance	(2)	(1)
Net unrealized gains (losses) on derivatives still held included in earnings	$ (1)	(1)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liabilities, CME Rule 814 adjustments		$ 0

Fair Value Measurement Schedule of Valuation Processes (Detail) - Level 3 - Market Approach Valuation Technique $ in Millions	Dec. 31, 2018 USD ($) $ / gal
Derivative Liabilities \| Natural Gas
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Liabilities, fair value \| $	$ (2)
Derivative Liabilities \| Natural Gas \| Minimum
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Forward Curve Range	2.46
Derivative Liabilities \| Natural Gas \| Maximum
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Forward Curve Range	2.88
Derivative Assets \| Natural Gas Liquids
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Assets, fair value \| $	$ 14
Derivative Assets \| Natural Gas Liquids \| Minimum
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Forward Curve Range	0.31
Derivative Assets \| Natural Gas Liquids \| Maximum
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Forward Curve Range	0.96
Derivative Assets \| Natural Gas
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Assets, fair value \| $	$ 2
Derivative Assets \| Natural Gas \| Minimum
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Forward Curve Range	2.01
Derivative Assets \| Natural Gas \| Maximum
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Forward Curve Range	2.56

Fair Value Measurement Carrying Value and Fair Value of Debt (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Total Debt, Carrying Value	$ 5,337	$ 4,736
Total Debt, Fair Value	$ 5,170	$ 4,885

Fair Value Measurement Schedule of Assets Measured at Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset impairments	$ 145	$ 48	$ 0
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure	0	1
Indefinite-lived Intangible Assets (Excluding Goodwill), Fair Value Disclosure	0	11
Property, Plant, and Equipment, Fair Value Disclosure	15	14
Asset Impairments	145	48
Assets, Fair Value Disclosure, Nonrecurring	15	26
Property, Plant and Equipment [Member] \| Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairments	145	26
Intangible Assets [Member] \| Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairments	0	21
Investment in unconsolidated affiliate [Member] \| Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairments	$ 0	$ 1

Debt - Schedule of Debt (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Aug. 01, 2018	Dec. 31, 2017
Facility [Line Items]
Fair value adjustments related to interest rate swap fair value hedges	$ 21		$ 23
Unamortized issuance costs	(30)		(29)
Unamortized discount	(10)		(12)
Total debt	5,307		4,707
Current debt	525		0
Long-term debt	4,782		4,707
Credit Agreement
Facility [Line Items]
Credit Facility	$ 351		0
Weighted-average variable interest rate	3.901%
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,400
Accounts Receivable Securitization Facility
Facility [Line Items]
Accounts Receivable Securitization Agreement	$ 200		0
Weighted-average variable interest rate	3.303%
Line of Credit Facility, Maximum Borrowing Capacity	$ 200
Accounts Recievable included in the Securitization Transaction	$ 831
Senior Notes \| Issued November 2012, interest at 2.500% payable semi-annually, due December 2017
Facility [Line Items]
Debt interest rate percentage	2.50%
Senior Notes \| Senior Notes Issued February 2009, interest at 9.750% payable semiannually, due March 2019
Facility [Line Items]
Senior Notes	$ 0	$ 450	450
Debt interest rate percentage	9.75%	9.75%
Senior Notes \| Issued March 2014, interest at 2.700% payable semi-annually, due April 2019
Facility [Line Items]
Senior Notes	$ 325		325
Debt interest rate percentage	2.70%
Senior Notes \| Issued March 2010, interest at 5.350% payable semiannually, due March 2020
Facility [Line Items]
Senior Notes	$ 600		600
Debt interest rate percentage	5.35%
Senior Notes \| Issued September 2011, interest at 4.750% payable semiannually, due September 2021
Facility [Line Items]
Senior Notes	$ 500		500
Debt interest rate percentage	4.75%
Senior Notes \| Issued March 2012, interest at 4.950% payable semi-annually, due April 2022
Facility [Line Items]
Senior Notes	$ 350		350
Debt interest rate percentage	4.95%
Senior Notes \| Issued March 2013, interest at 3.875% payable semi-annually, due March 2023
Facility [Line Items]
Senior Notes	$ 500		500
Debt interest rate percentage	3.875%
Senior Notes \| Issued July 2018, interest at 5.375% payable semi-annually, due July 2025
Facility [Line Items]
Senior Notes	$ 500		0
Debt interest rate percentage	5.375%
Senior Notes \| Issued August 2000, interest at 8.125% payable semi-annually, due August 2030
Facility [Line Items]
Senior Notes	$ 300		300
Debt interest rate percentage	8.125%
Senior Notes \| Issued October 2006, interest at 6.450% payable semi-annually, due November 2036
Facility [Line Items]
Senior Notes	$ 300		300
Debt interest rate percentage	6.45%
Senior Notes \| Issued September 2007, interest at 6.750% payable semi-annually, due September 2037
Facility [Line Items]
Senior Notes	$ 450		450
Debt interest rate percentage	6.75%
Senior Notes \| Issued March 2014, interest at 5.600% payable semi-annually, due April 2044
Facility [Line Items]
Senior Notes	$ 400		400
Debt interest rate percentage	5.60%
Junior subordinated notes \| Issued May 2013, interest at 5.850% payable semi-annually, due May 2043
Facility [Line Items]
Senior Notes	$ 550		$ 550
Debt interest rate percentage	5.85%

Debt - Additional Information (Detail) $ in Millions			12 Months Ended
Debt - Additional Information (Detail) $ in Millions	Aug. 01, 2018 USD ($)	Jul. 17, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Loss on Redemption of Debt			$ (19)	$ 0	$ 0
Line of Credit Facility, Borrowing Capacity, Description			$ 500
Interest deferment period			5 years
Accounts Receivable Securitization Facility
Debt Instrument [Line Items]
Accounts Recievable included in the Securitization Transaction			$ 831
Line of Credit Facility, Maximum Borrowing Capacity			200
Credit Agreement
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 1,400
Basis spread determined by credit rating			0.45%
Commitment fee percentage			0.30%
Unused capacity under the credit agreement			$ 1,036
Letter of credit amount outstanding			13
Debt covenants, maximum borrowing amount			$ 1,036
Credit Agreement \| LIBOR
Debt Instrument [Line Items]
Variable rate basis spread			1.45%
Credit Agreement \| Federal Funds Rate
Debt Instrument [Line Items]
Variable rate basis spread			0.50%
Credit Agreement \| LIBOR Market Index
Debt Instrument [Line Items]
Variable rate basis spread			1.00%
Credit Agreement \| Maximum
Debt Instrument [Line Items]
Maximum leverage ratio in event of acquisition			5.50
Credit Agreement \| Quarters After June 30, 2018 \| Maximum
Debt Instrument [Line Items]
Maximum leverage ratio			5.00
Senior Notes Issued February 2009, interest at 9.750% payable semiannually, due March 2019 \| Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 450		$ 0	$ 450
Gross Redemption Payment	$ 468
Debt Instrument, Redemption Price, Percentage	104.00831%
Loss on Redemption of Debt	$ (19)
Debt Instrument, Interest Rate, Stated Percentage	9.75%		9.75%
Senior Notes Issued July 2018, interest at 5.375% payable semiannually, due July 2025 \| Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 500
Debt Instrument, Interest Rate, Stated Percentage		5.375%
Proceeds from Issuance of Senior Long-term Debt		$ 495

Debt - Future Maturities of Long-Term Debt (Detail) $ in Millions	Dec. 31, 2018 USD ($)
Maturities of Long-term Debt [Abstract]
2019	$ 525
2020	600
2021	500
2022	701
2023	500
Thereafter	2,500
Long Term Debt Maturities Repayments Of Principal Total	$ 5,326

Risk Management and Hedging Activities - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Accumulated other comprehensive loss	$ (8)	$ (9)
Collateral, cash deposits	34
Collateral, cash held	13
Letters of credit received	105
Accumulated Net Gain (Loss) from Cash Flow Hedges
Derivative [Line Items]
Accumulated other comprehensive loss	(8)	(9)	$ (8)
Accumulated Net Gain (Loss) from Cash Flow Hedges \| Commodity derivatives
Derivative [Line Items]
Accumulated other comprehensive loss	$ (6)	$ (6)	$ (6)

Risk Management and Hedging Activities - Summary of Gross and Net Amounts of Derivative Instruments (Detail) - Commodity derivatives - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Offsetting Assets [Line Items]
Gross Amounts of Assets Presented in the Balance Sheet	$ 116	$ 33
Amounts Not Offset in the Balance Sheet - Financial Instruments	0	0
Net Amount	116	33
Offsetting Liabilities [Line Items]
Gross Amounts of Liabilities Presented in the Balance Sheet	(99)	(91)
Amounts Not Offset in the Balance Sheet - Financial Instruments	0	0
Net Amount	$ (99)	$ (91)

Risk Management and Hedging Activities - Schedule of Designated and Non-Designated Derivative Instruments in Statement of Financial Position, Fair Value (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivative Asset [Abstract]
Derivative Instruments and Hedges, Current Assets	$ 108	$ 30
Derivative Instruments and Hedges, Assets, Noncurrent	8	3
Derivative Liability [Abstract]
Derivative Instruments and Hedges, Current Liabilities	91	76
Derivative Instruments and Hedges, Liabilities, Noncurrent	8	15
Commodity derivatives \| Derivative Asset Not Designated As Hedging Instruments [Member]
Derivative Asset [Abstract]
Derivative Instruments and Hedges, Current Assets	108	30
Derivative Instruments and Hedges, Assets, Noncurrent	8	3
Derivative Instruments Not Designated as Hedging Instruments, Total Assets, at Fair Value	116	33
Commodity derivatives \| Derivative Liabilities Not Designated As Hedging Instruments [Member]
Derivative Liability [Abstract]
Derivative Instruments and Hedges, Current Liabilities	91	76
Derivative Instruments and Hedges, Liabilities, Noncurrent	8	15
Derivative Instruments Not Designated as Hedging Instruments, Total Liabilities, at Fair Value	$ 99	$ 91

Risk Management and Hedging Activities - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Accumulated Other Comprehensive (Loss) Income	$ (8)	$ (9)
Accumulated Net Gain (Loss) from Cash Flow Hedges
Derivative [Line Items]
Accumulated Other Comprehensive (Loss) Income	(8)	(9)	$ (8)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1
Accumulated Net Gain (Loss) from Cash Flow Hedges \| Interest Rate Derivatives
Derivative [Line Items]
Accumulated Other Comprehensive (Loss) Income	(3)	(4)	(3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1
Accumulated Net Gain (Loss) from Cash Flow Hedges \| Commodity derivatives
Derivative [Line Items]
Accumulated Other Comprehensive (Loss) Income	(6)	(6)	(6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0
Accumulated Net Gain (Loss) from Cash Flow Hedges \| Foreign Currency Derivatives
Derivative [Line Items]
Accumulated Other Comprehensive (Loss) Income	1	1	$ 1
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0
Cash Flow Hedging [Member]
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	(1)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		1
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		(2)
Cash Flow Hedging [Member] \| Interest Rate Derivatives
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	(1)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		1
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		(2)
Cash Flow Hedging [Member] \| Commodity derivatives
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		0
Cash Flow Hedging [Member] \| Foreign Currency Derivatives
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		$ 0

Risk Management and Hedging Activities - Schedule of Changes in Derivative Instruments not Designated as Hedging Instruments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Trading and marketing gains, net	$ (41)	$ (40)	$ (23)
Derivative Assets Not Designated As Hedging Instruments \| Third Party \| Commodity derivatives
Derivative [Line Items]
Realized (losses) gains	(149)	(12)	116
Unrealized gains (losses)	108	(28)	(139)
Trading and marketing gains, net	$ (41)	$ (40)	$ (23)

Risk Management and Hedging Activities - Schedule of Net Long or Short Positions Expected to be Realized (Detail)	12 Months Ended
	Dec. 31, 2018 MMBTU bbl	Dec. 31, 2017 MMBTU bbl
Crude Oil
Net (Short) Position, Volume [Abstract]
Net (Short) Position (Bbls), Year One \| bbl	(1,619,000)	(2,701,000)
Net (Short) Position (Bbls), Year Two \| bbl	(204,000)	(631,000)
Net (Short) Long Position (Bbls), Year Three \| bbl	0	(50,000)
Natural Gas
Net Long (Short) Position, MMBtu [Abstract]
Net (Short) Long Position (MMBtu), Year One \| MMBTU	(40,291,250)	(35,977,400)
Net Long Position (MMBtu), Year Two \| MMBTU	0	0
Net (Short) Long Position (MMBtu), Year Three \| MMBTU	0	0
Natural Gas Liquids
Net (Short) Position, Volume [Abstract]
Net (Short) Position (Bbls), Year One \| bbl	(36,312,499)	(19,656,392)
Net (Short) Position (Bbls), Year Two \| bbl	(13,862,378)	(2,357,156)
Net (Short) Long Position (Bbls), Year Three \| bbl	(5,755,322)	238,548
Natural Gas Basis Swaps
Net Long (Short) Position, MMBtu [Abstract]
Net (Short) Long Position (MMBtu), Year One \| MMBTU	(2,165,000)	3,202,500
Net Long Position (MMBtu), Year Two \| MMBTU	3,660,000	7,177,500
Net (Short) Long Position (MMBtu), Year Three \| MMBTU	(3,650,000)	3,660,000

Partnership Equity and Distributions - Additional Information (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares Rate
Partnership Equity And Distribution [Line Items]
Limited Partner Ownership Interest \| Rate	36.00%
General Partner Ownership Interest \| Rate	2.00%
Incentive Distribution, Potential Annual Reduction \| $	$ 100
Incentive Distribution, Potential Quarterly Reduction \| $	20
Incentive Distribution, repayment \| $	$ 40
Distribution Coverage Ratio, Target	1.0
Equity Distribution Agreement [Member]
Partnership Equity And Distribution [Line Items]
Offer Value Of Common Stock Unit Remaining Available For Sale \| $	$ 750
Distribution Stage First [Member]
Partnership Equity And Distribution [Line Items]
Distribution made to Unitholders and General Partner, Per Unit \| $ / shares	$ 0.4025
Distribution Stage Second [Member]
Partnership Equity And Distribution [Line Items]
Distribution made to Unitholders and General Partner, Per Unit \| $ / shares	$ 0.4375
Incentive Distribution, Payments Made and Minimum Distribution Level	0.13
Distribution Stage Third [Member]
Partnership Equity And Distribution [Line Items]
Distribution made to Unitholders and General Partner, Per Unit \| $ / shares	$ 0.5250
Incentive Distribution, Payments Made and Minimum Distribution Level	0.23
Distribution Stage Thereafter [Member]
Partnership Equity And Distribution [Line Items]
Distribution made to Unitholders and General Partner, Per Unit \| $ / shares	$ 0.4800

Partnership Equity and Distributions - Cash Distribution (Detail) - USD ($) $ / shares in Units, $ in Millions																12 Months Ended
	Dec. 17, 2018	Nov. 14, 2018	Sep. 17, 2018	Aug. 14, 2018	Jun. 15, 2018	May 15, 2018	Feb. 14, 2018	Nov. 14, 2017	Aug. 14, 2017	May 15, 2017	Feb. 14, 2017	Nov. 14, 2016	Aug. 12, 2016	May 13, 2016	Feb. 12, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Distribution Made to Limited Partner [Line Items]
Total Cash Distribution																$ 706	$ 545	$ 483
Series A Preferred Limited Partners [Member]
Distribution Made to Limited Partner [Line Items]
Preferred Limited Partnership Distribution; Distribution Amount Paid	$ 36.875				$ 41.9965
Total Cash Distribution	$ 18				$ 21											39
Series B Preferred Limited Partners [Member]
Distribution Made to Limited Partner [Line Items]
Preferred Limited Partnership Distribution; Distribution Amount Paid	$ 0.4922		$ 0.6781
Total Cash Distribution	$ 3		$ 4													7
Limited Partners
Distribution Made to Limited Partner [Line Items]
Per Unit Distribution (in dollars per share)		$ 0.78		$ 0.78		$ 0.78	$ 0.78	$ 0.78	$ 0.78	$ 0.78	$ 0.78	$ 0.78	$ 0.78	$ 0.78	$ 0.78
Total Cash Distribution		$ 155		$ 154		$ 155	$ 194	$ 155	$ 134	$ 135	$ 121	$ 120	$ 121	$ 121	$ 121	$ 447	$ 425	$ 359

Partnership Equity and Distributions (To Supercede) Partnership Equity and Distributions Preferred Series B Distributions (Details) - USD ($) $ in Millions		12 Months Ended
	May 11, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Preferred Units [Line Items]
Proceeds from Issuance of Preferred Limited Partners Units		$ 261	$ 487	$ 0
Series B Preferred Limited Partners [Member]
Preferred Units [Line Items]
Preferred Units, Issued	6,450,000	6,450,000	0
Proceeds from Issuance of Preferred Limited Partners Units	$ 155	$ 155

Partnership Equity and Distributions Partnership Equity and Distributions - Preferred Issuance (Details) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Oct. 04, 2018	May 11, 2018	Nov. 20, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Preferred Units [Line Items]
Proceeds from Issuance of Preferred Limited Partners Units				$ 261	$ 487	$ 0
Series C Preferred Limited Partners [Member]
Preferred Units [Line Items]
Preferred Units, Issued	4,400,000			4,400,000	0
Units Sold Under Private Placement Price Per Unit	$ 25
Proceeds from Issuance of Preferred Limited Partners Units	$ 106			$ 106
Preferred Limited Partner Unit Distribution, Annual Per Unit	$ 1.9875
Preferred Limited Partnership Unit Distribution; Distribution Rate	7.95%
Series C Preferred Limited Partners [Member] \| On and after October 15, 2023 [Member]
Preferred Units [Line Items]
Preferred Limited Partnership Unit Distribution; Distribution Rate	4.88%
Series B Preferred Limited Partners [Member]
Preferred Units [Line Items]
Preferred Units, Issued		6,450,000		6,450,000	0
Proceeds from Issuance of Preferred Limited Partners Units		$ 155		$ 155
Series A Preferred Limited Partners [Member]
Preferred Units [Line Items]
Preferred Units, Issued				500,000	500,000
Proceeds from Issuance of Preferred Limited Partners Units			$ 487	$ 0	$ 487

Equity-Based Compensation (Details) - USD ($) $ in Millions	12 Months Ended
Equity-Based Compensation (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 28, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 11	$ 23	$ 18
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated Forfeiture Rate	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated Forfeiture Rate	11.00%
Strategic Performance Units (SPUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum vesting percentage	200.00%
Vesting Period (years)	3 years
Phantom Share Units (PSUs) \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period (years)	1 year
Phantom Share Units (PSUs) \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period (years)	3 years
Two Thousand Sixteen Long-Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Units Authorized, in Shares				900,000

- Fair Value of Unvested Unit-Based Awards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Strategic Performance Units (SPUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period (years)	3 years
Unrecognized Compensation Expense at December 31, 2017 (millions)	$ 4
Maximum vesting percentage	200.00%
Weighted-Average Remaining Vesting (years)	2 years
Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense at December 31, 2017 (millions)	$ 4
Weighted-Average Remaining Vesting (years)	2 years
Phantom Units \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period (years)	1 year
Phantom Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period (years)	3 years

- Schedule of Units Outstanding (Details) - $ / shares	12 Months Ended
- Schedule of Units Outstanding (Details) - $ / shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	231,706	201,081	207,317	204,368
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 42.55	$ 52.18	$ 46.80	$ 49.85
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	242,780	180,337	132,870
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 36.87	$ 59.43	$ 45.33
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(17,696)	(16,677)	(3,240)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 45.35	$ 51.73	$ 48.62
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(194,459)	(169,896)	(126,681)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 45.16	$ 53.35	$ 50.13
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Measurement Date Fair Value, Ending Balance	$ 33.08
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Expected to Vest	215,482
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value, Expected to Vest	$ 42.52
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Measurement Date Fair Value, Expected to Vest	$ 33.06
Strategic Performance Units (SPUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	251,319	214,735	233,311	208,459
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 43.33	$ 51.98	$ 44.41	$ 48.46
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	168,160	98,628	131,610
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 36.23	$ 76.38	$ 45.31
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(10,933)	(18,577)	(8,463)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 47.79	$ 50.31	$ 46.27
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(120,643)	(98,627)	(98,295)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 48.41	$ 58.80	$ 54.05
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Measurement Date Fair Value, Ending Balance	$ 34.30
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Expected to Vest	231,936
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value, Expected to Vest	$ 43.54
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Measurement Date Fair Value, Expected to Vest	$ 34.53
Two-Thousand And Fourteen [Member] \| Strategic Performance Units (SPUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			130.00%
Two-Thousand And Fifteen [Member] [Domain] \| Strategic Performance Units (SPUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		180.00%
Two-Thousand And Sixteen [Member] \| Strategic Performance Units (SPUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	165.00%

Equity-Based Compensation - Fair Value of Awards Vested (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	194,459	169,896	126,681
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 5	$ 7	$ 4
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid	$ 7	$ 4	$ 5
Strategic Performance Units (SPUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	120,643	98,627	98,295
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 9	$ 11	$ 7
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid	$ 11	$ 7	$ 4

Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]
Eligibility minimum age	18 years
Eligibility hours per week	20 hours
Automatic enrollment percentage	6.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	6.00%
Defined contribution cost	$ 30	$ 29	$ 29
Minimum
Defined Contribution Plan Disclosure [Line Items]
Employer discretionary contribution percentage	4.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Employer discretionary contribution percentage	7.00%

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)	$ 0	$ 0	$ 19
Current state income tax expense	0	(1)	(2)
Deferred federal income tax expense	0	0	(22)
Deferred State and Local Income Tax Expense (Benefit)	(3)	(1)	(3)
Income tax expense	(3)	(2)	(46)
Deferred income taxes	$ (32)	$ (29)
Increase (Decrease) In Deferred Tax Assets			$ 58
State gross margin tax rate (as percent)	0.75%	0.75%	0.75%

Commitments and Contingent Liabilities Commitments and Contingent Liabilities (Details) - USD ($)		12 Months Ended
	Feb. 14, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2019
Other Commitments [Line Items]
Operating Leases, Rent Expense		$ 30,000,000	$ 33,000,000	$ 37,000,000
Operating Leases, Future Minimum Payments, Remainder of Fiscal Year		22,000,000
Operating Leases, Future Minimum Payments, Due in Two Years		18,000,000
Operating Leases, Future Minimum Payments, Due in Three Years		14,000,000
Operating Leases, Future Minimum Payments, Due in Four Years		9,000,000
Operating Leases, Future Minimum Payments, Due in Five Years		5,000,000
Operating Leases, Future Minimum Payments, Due Thereafter		7,000,000
Operating Leases, Future Minimum Payments Due		75,000,000
Other Current Liabilities [Member]
Other Commitments [Line Items]
Accrual for Environmental Loss Contingencies		3,000,000	4,000,000
Long- Term Liabilities
Other Commitments [Line Items]
Accrual for Environmental Loss Contingencies		$ 8,000,000	$ 8,000,000
Subsequent Event [Member] \| New Mexico Environment Department Notice of Violation 1 [Member]
Other Commitments [Line Items]
Administrative Settlement Penalty	$ 149,832
Subsequent Event [Member] \| New Mexico Environment Department Notice of Violation 2 [Member]
Other Commitments [Line Items]
Administrative Settlement Penalty	$ 142,233
Subsequent Event [Member] \| Low end of estimate
Other Commitments [Line Items]
Estimated Litigation Liability					$ 195,000
Subsequent Event [Member] \| High end of estimate
Other Commitments [Line Items]
Estimated Litigation Liability					$ 240,000

Restructuring (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Restructuring (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring and Related Activities [Abstract]
Restructuring and Related Cost, Expected Number of Positions Eliminated, Percent	10.00%
Restructuring Cost and Reserve [Line Items]
Restructuring costs		$ 0	$ 0	$ 13
One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs				$ 13

Business Segments - Segment Information (Detail) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| Segment									2
Segment Reporting Information [Line Items]
Total operating revenues	$ 2,607	$ 2,759	$ 2,317	$ 2,139	$ 2,337	$ 2,055	$ 1,949	$ 2,121	$ 9,822	$ 8,462	$ 6,893
Gross margin									1,803	1,577	1,432
Operating and maintenance expense									(760)	(661)	(670)
Depreciation and amortization expense									(388)	(379)	(378)
General and administrative expense									(276)	(290)	(292)
Asset impairments									145	48	0
Other income (expense)									(11)	(11)	65
Loss from financing activities									(19)	0	0
Gain on sale of assets, net									0	34	35
Restructuring costs									0	0	13
Earnings from unconsolidated affiliates									370	303	282
Interest expense, net									(269)	(289)	(321)
Income tax expense									(3)	(2)	(46)
Net income	95	82	62	63	64	(20)	89	101	302	234	94
Net income attributable to noncontrolling interests	(1)	(1)	(1)	(1)	(4)	0	(1)	0	(4)	(5)	(6)
Net income attributable to partners	$ 94	$ 81	$ 61	$ 62	$ 60	$ (20)	$ 88	$ 101	298	229	88
Non-cash derivative mark-to-market									108	(28)	(139)
Non-cash lower of cost or market adjustment									0	(2)	(3)
Capital expenditures									595	375	144
Investments in unconsolidated affiliates, net									354	148	53
Logistics and Marketing
Segment Reporting Information [Line Items]
Total operating revenues									9,014
Gathering and Processing
Segment Reporting Information [Line Items]
Total operating revenues									5,843
Operating Segments \| Logistics and Marketing
Segment Reporting Information [Line Items]
Total operating revenues									9,014	7,757	6,186
Gross margin									225	200	205
Operating and maintenance expense									(47)	(41)	(43)
Depreciation and amortization expense									(15)	(14)	(15)
General and administrative expense									(12)	(11)	(9)
Asset impairments									0	0
Other income (expense)									(4)	(11)	(5)
Loss from financing activities									0
Gain on sale of assets, net										0	16
Restructuring costs											0
Earnings from unconsolidated affiliates									362	243	209
Interest expense, net									0	0	0
Income tax expense									0	0	0
Net income									509	366	358
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to partners									509	366	358
Non-cash derivative mark-to-market									(4)	(4)	(20)
Non-cash lower of cost or market adjustment										(2)	(3)
Capital expenditures									8	3	10
Investments in unconsolidated affiliates, net									350	147	52
Operating Segments \| Gathering and Processing
Segment Reporting Information [Line Items]
Total operating revenues									5,843	5,467	4,490
Gross margin									1,578	1,377	1,227
Operating and maintenance expense									(692)	(602)	(611)
Depreciation and amortization expense									(346)	(343)	(344)
General and administrative expense									(19)	(19)	(14)
Asset impairments									145	48
Other income (expense)									(6)	0	73
Loss from financing activities									0
Gain on sale of assets, net										34	19
Restructuring costs											0
Earnings from unconsolidated affiliates									8	60	73
Interest expense, net									0	0	0
Income tax expense									0	0	0
Net income									378	459	423
Net income attributable to noncontrolling interests									(4)	(5)	(6)
Net income attributable to partners									374	454	417
Non-cash derivative mark-to-market									112	(24)	(119)
Non-cash lower of cost or market adjustment										0	0
Capital expenditures									570	350	107
Investments in unconsolidated affiliates, net									4	1	1
Other
Segment Reporting Information [Line Items]
Total operating revenues									0	0	0
Gross margin									0	0	0
Operating and maintenance expense									(21)	(18)	(16)
Depreciation and amortization expense									(27)	(22)	(19)
General and administrative expense									(245)	(260)	(269)
Asset impairments									0	0
Other income (expense)									(1)	0	(3)
Loss from financing activities									(19)
Gain on sale of assets, net										0	0
Restructuring costs											13
Earnings from unconsolidated affiliates									0	0	0
Interest expense, net									(269)	(289)	(321)
Income tax expense									(3)	(2)	(46)
Net income									(585)	(591)	(687)
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to partners									(585)	(591)	(687)
Non-cash derivative mark-to-market									0	0	0
Non-cash lower of cost or market adjustment										0	0
Capital expenditures									17	22	27
Investments in unconsolidated affiliates, net									0	0	0
Eliminations
Segment Reporting Information [Line Items]
Total operating revenues									(5,035)	(4,762)	(3,783)
Gross margin									0	0	0
Operating and maintenance expense										0	0
Depreciation and amortization expense									0	0	0
General and administrative expense									0	0	0
Asset impairments									0	0
Other income (expense)										0	0
Loss from financing activities									0
Gain on sale of assets, net									0	0	0
Restructuring costs											0
Earnings from unconsolidated affiliates									0	0	0
Interest expense, net									0	0	0
Income tax expense									0	0	0
Net income									0	0	0
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to partners									0	0	0
Non-cash derivative mark-to-market										0	0
Non-cash lower of cost or market adjustment									0	0	0
Capital expenditures									0	0	0
Investments in unconsolidated affiliates, net									$ 0	$ 0	$ 0

Business Segments - Segment Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Segment long-term assets	$ 12,995	$ 12,556
Current assets	1,271	1,322
Total assets	14,266	13,878
Operating Segments \| Logistics and Marketing
Segment Reporting, Asset Reconciling Item [Line Items]
Segment long-term assets	3,661	3,348
Operating Segments \| Gathering and Processing
Segment Reporting, Asset Reconciling Item [Line Items]
Segment long-term assets	9,058	8,943
Other
Segment Reporting, Asset Reconciling Item [Line Items]
Segment long-term assets	$ 276	$ 265

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(14))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(10))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(12))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(15))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(11))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(13))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(17))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(16))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net of amounts capitalized	$ 259	$ 290	$ 306
Income Taxes Paid, Net	3	2	2
Noncash Investing and Financing Items [Abstract]
Property, plant and equipment acquired with accounts payable and accrued liabilities	99	58	27
Property, Plant and Equipment, Other Increase (Decrease)	$ 5	$ 5	$ (3)

Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data (Unaudited) [Abstract]
Total operating revenues	$ 2,607	$ 2,759	$ 2,317	$ 2,139	$ 2,337	$ 2,055	$ 1,949	$ 2,121	$ 9,822	$ 8,462	$ 6,893
Operating Income (Loss)	70	66	34	53	62	(19)	78	101	223	222	179
Net income	95	82	62	63	64	(20)	89	101	302	234	94
Net income attributable to noncontrolling interests	(1)	(1)	(1)	(1)	(4)	0	(1)	0	(4)	(5)	(6)
Net Income (Loss) Attributable to Parent	94	81	61	62	60	(20)	88	101	298	229	88
Net Income (Loss) Allocated to Limited Partners	$ 39	$ 26	$ 10	$ 12	$ 14	$ (59)	$ 47	$ 59	$ 87	$ 61	$ 188
Net income per limited partner unit — basic and diluted	$ 0.28	$ 0.18	$ 0.07	$ 0.08	$ 0.10	$ (0.41)	$ 0.33	$ 0.41	$ 0.61	$ 0.43	$ 1.64
Net loss attributable to predecessor operations									$ 0	$ 0	$ 224

Condensed Consolidating Financial Information - Condensed Consolidating Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Cash and cash equivalents	$ 1	$ 156	$ 1	$ 3
Accounts receivable, net	1,033	981
Inventories	79	68
Other	158	117
Total current assets	1,271	1,322
Property, plant and equipment, net	9,135	8,983
Goodwill and intangible assets, net	328	337
Advances receivable — consolidated subsidiaries	0	0
Investments in unconsolidated affiliates	0	0
Investments in unconsolidated affiliates	3,340	3,050
Other long-term assets	192	186
Total assets	14,266	13,878
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	1,379	1,488
Current debt	525	0
Advances payable — consolidated subsidiaries	0	0
Long-term debt	4,782	4,707
Other long-term liabilities	283	245
Total liabilities	6,969	6,440
Commitments and contingent liabilities (see note 14)
Equity:
Net equity	7,276	7,417
Accumulated other comprehensive loss	(8)	(9)
Total partners’ equity	7,268	7,408
Noncontrolling interests	29	30
Total equity	7,297	7,438	6,853	7,092
Total liabilities and equity	14,266	13,878
Reportable Legal Entities \| Parent Guarantor
ASSETS
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Inventories	0	0
Other	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill and intangible assets, net	0	0
Advances receivable — consolidated subsidiaries	2,452	2,895
Investments in unconsolidated affiliates	4,818	4,513
Investments in unconsolidated affiliates	0	0
Other long-term assets	0	0
Total assets	7,270	7,408
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	2	0
Current debt	0
Advances payable — consolidated subsidiaries	0	0
Long-term debt	0	0
Other long-term liabilities	0	0
Total liabilities	2	0
Commitments and contingent liabilities (see note 14)
Equity:
Net equity	7,268	7,408
Accumulated other comprehensive loss	0	0
Total partners’ equity	7,268	7,408
Noncontrolling interests	0	0
Total equity	7,268	7,408
Total liabilities and equity	7,270	7,408
Reportable Legal Entities \| Subsidiary Issuer
ASSETS
Cash and cash equivalents	0	155	0	0
Accounts receivable, net	0	0
Inventories	0	0
Other	0	0
Total current assets	0	155
Property, plant and equipment, net	0	0
Goodwill and intangible assets, net	0	0
Advances receivable — consolidated subsidiaries	1,883	1,614
Investments in unconsolidated affiliates	8,113	7,522
Investments in unconsolidated affiliates	0	0
Other long-term assets	0	0
Total assets	9,996	9,291
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	71	71
Current debt	325
Advances payable — consolidated subsidiaries	0	0
Long-term debt	4,782	4,707
Other long-term liabilities	0	0
Total liabilities	5,178	4,778
Commitments and contingent liabilities (see note 14)
Equity:
Net equity	4,821	4,517
Accumulated other comprehensive loss	(3)	(4)
Total partners’ equity	4,818	4,513
Noncontrolling interests	0	0
Total equity	4,818	4,513
Total liabilities and equity	9,996	9,291
Reportable Legal Entities \| Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	1	1	1	3
Accounts receivable, net	1,033	981
Inventories	79	68
Other	158	117
Total current assets	1,271	1,167
Property, plant and equipment, net	9,135	8,983
Goodwill and intangible assets, net	328	337
Advances receivable — consolidated subsidiaries	0	0
Investments in unconsolidated affiliates	0	0
Investments in unconsolidated affiliates	3,340	3,050
Other long-term assets	192	186
Total assets	14,266	13,723
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	1,306	1,417
Current debt	200
Advances payable — consolidated subsidiaries	4,335	4,509
Long-term debt	0	0
Other long-term liabilities	283	245
Total liabilities	6,124	6,171
Commitments and contingent liabilities (see note 14)
Equity:
Net equity	8,118	7,527
Accumulated other comprehensive loss	(5)	(5)
Total partners’ equity	8,113	7,522
Noncontrolling interests	29	30
Total equity	8,142	7,552
Total liabilities and equity	14,266	13,723
Consolidating Adjustments
ASSETS
Cash and cash equivalents	0	0	$ 0	$ 0
Accounts receivable, net	0	0
Inventories	0	0
Other	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill and intangible assets, net	0	0
Advances receivable — consolidated subsidiaries	(4,335)	(4,509)
Investments in unconsolidated affiliates	(12,931)	(12,035)
Investments in unconsolidated affiliates	0	0
Other long-term assets	0	0
Total assets	(17,266)	(16,544)
LIABILITIES AND EQUITY
Accounts payable and other current liabilities	0	0
Current debt	0
Advances payable — consolidated subsidiaries	(4,335)	(4,509)
Long-term debt	0	0
Other long-term liabilities	0	0
Total liabilities	(4,335)	(4,509)
Commitments and contingent liabilities (see note 14)
Equity:
Net equity	(12,931)	(12,035)
Accumulated other comprehensive loss	0	0
Total partners’ equity	(12,931)	(12,035)
Noncontrolling interests	0	0
Total equity	(12,931)	(12,035)
Total liabilities and equity	$ (17,266)	$ (16,544)

Condensed Consolidating Financial Information - Condensed Consolidating Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating revenues:
Sales of natural gas, NGLs and condensate									$ 9,374	$ 7,850	$ 6,269
Transportation, processing and other									489	652	647
Trading and marketing losses, net									(41)	(40)	(23)
Total operating revenues	$ 2,607	$ 2,759	$ 2,317	$ 2,139	$ 2,337	$ 2,055	$ 1,949	$ 2,121	9,822	8,462	6,893
Purchases and related costs									8,019	6,885	5,461
Operating and maintenance expense									760	661	670
Depreciation and amortization expense									388	379	378
General and administrative expense									276	290	292
Asset impairments									145	48	0
Gain on sale of assets, net									0	34	35
Restructuring costs									0	0	13
Other income (expense)									(11)	(11)	65
Costs and Expenses									9,599	8,240	6,714
Operating income	70	66	34	53	62	(19)	78	101	223	222	179
Loss from financing activities									(19)	0	0
Interest expense, net									(269)	(289)	(321)
Income from consolidated subsidiaries									0	0	0
Earnings from unconsolidated affiliates									370	303	282
Income before income taxes									305	236	140
Income tax expense									(3)	(2)	(46)
Net income	95	82	62	63	64	(20)	89	101	302	234	94
Net income attributable to noncontrolling interests	(1)	(1)	(1)	(1)	(4)	0	(1)	0	(4)	(5)	(6)
Net income attributable to partners	$ 94	$ 81	$ 61	$ 62	$ 60	$ (20)	$ 88	$ 101	298	229	88
Reportable Legal Entities \| Parent Guarantor
Operating revenues:
Sales of natural gas, NGLs and condensate									0	0	0
Transportation, processing and other									0	0	0
Trading and marketing losses, net									0	0	0
Total operating revenues									0	0	0
Purchases and related costs									0	0	0
Operating and maintenance expense									0	0	0
Depreciation and amortization expense									0	0	0
General and administrative expense									0	0	0
Asset impairments									0	0
Gain on sale of assets, net										0	0
Restructuring costs											0
Other income (expense)									0	0	0
Costs and Expenses									0	0	0
Operating income									0	0	0
Loss from financing activities									0
Interest expense, net									0	0	0
Income from consolidated subsidiaries									298	229	88
Earnings from unconsolidated affiliates									0	0	0
Income before income taxes									298	229	88
Income tax expense									0	0	0
Net income									298	229	88
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to partners									298	229	88
Reportable Legal Entities \| Subsidiary Issuer
Operating revenues:
Sales of natural gas, NGLs and condensate									0	0	0
Transportation, processing and other									0	0	0
Trading and marketing losses, net									0	0	0
Total operating revenues									0	0	0
Purchases and related costs									0	0	0
Operating and maintenance expense									0	0	0
Depreciation and amortization expense									0	0	0
General and administrative expense									0	0	0
Asset impairments									0	0
Gain on sale of assets, net										0	0
Restructuring costs											0
Other income (expense)									0	0	0
Costs and Expenses									0	0	0
Operating income									0	0	0
Loss from financing activities									(19)
Interest expense, net									(268)	(289)	(321)
Income from consolidated subsidiaries									585	518	409
Earnings from unconsolidated affiliates									0	0	0
Income before income taxes									298	229	88
Income tax expense									0	0	0
Net income									298	229	88
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to partners									298	229	88
Reportable Legal Entities \| Non-Guarantor Subsidiaries
Operating revenues:
Sales of natural gas, NGLs and condensate									9,374	7,850	6,269
Transportation, processing and other									489	652	647
Trading and marketing losses, net									(41)	(40)	(23)
Total operating revenues									9,822	8,462	6,893
Purchases and related costs									8,019	6,885	5,461
Operating and maintenance expense									760	661	670
Depreciation and amortization expense									388	379	378
General and administrative expense									276	290	292
Asset impairments									145	48
Gain on sale of assets, net										34	35
Restructuring costs											13
Other income (expense)									(11)	(11)	65
Costs and Expenses									9,599	8,240	6,714
Operating income									223	222	179
Loss from financing activities									0
Interest expense, net									(1)	0	0
Income from consolidated subsidiaries									0	0	0
Earnings from unconsolidated affiliates									370	303	282
Income before income taxes									592	525	461
Income tax expense									(3)	(2)	(46)
Net income									589	523	415
Net income attributable to noncontrolling interests									(4)	(5)	(6)
Net income attributable to partners									585	518	409
Consolidating Adjustments
Operating revenues:
Sales of natural gas, NGLs and condensate									0	0	0
Transportation, processing and other									0	0	0
Trading and marketing losses, net									0	0	0
Total operating revenues									0	0	0
Purchases and related costs									0	0	0
Operating and maintenance expense									0	0	0
Depreciation and amortization expense									0	0	0
General and administrative expense									0	0	0
Asset impairments									0	0
Gain on sale of assets, net										0	0
Restructuring costs											0
Other income (expense)									0	0	0
Costs and Expenses									0	0	0
Operating income									0	0	0
Loss from financing activities									0
Interest expense, net									0	0	0
Income from consolidated subsidiaries									(883)	(747)	(497)
Earnings from unconsolidated affiliates									0	0	0
Income before income taxes									(883)	(747)	(497)
Income tax expense									0	0	0
Net income									(883)	(747)	(497)
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to partners									(883)	(747)	(497)
Eliminations
Operating revenues:
Total operating revenues									(5,035)	(4,762)	(3,783)
Operating and maintenance expense										0	0
Depreciation and amortization expense									0	0	0
General and administrative expense									0	0	0
Asset impairments									0	0
Gain on sale of assets, net									0	0	0
Restructuring costs											0
Other income (expense)										0	0
Loss from financing activities									0
Interest expense, net									0	0	0
Earnings from unconsolidated affiliates									0	0	0
Income tax expense									0	0	0
Net income									0	0	0
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to partners									$ 0	$ 0	$ 0

Condensed Consolidating Financial Information - Condensed Consolidating Statement of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net income	$ 95	$ 82	$ 62	$ 63	$ 64	$ (20)	$ 89	$ 101	$ 302	$ 234	$ 94
Other comprehensive income (loss):
Reclassification of cash flow hedge losses into earnings									1	1	0
Other comprehensive income from consolidated subsidiaries									0	0
Total other comprehensive income									1	1	0
Total comprehensive income									303	235	94
Total comprehensive income attributable to noncontrolling interests									(4)	(5)	(6)
Total comprehensive income attributable to partners									299	230	88
Reportable Legal Entities \| Parent Guarantor
Condensed Financial Statements, Captions [Line Items]
Net income									298	229	88
Other comprehensive income (loss):
Reclassification of cash flow hedge losses into earnings									0	0
Other comprehensive income from consolidated subsidiaries									1	1
Total other comprehensive income									1	1	0
Total comprehensive income									299	230	88
Total comprehensive income attributable to noncontrolling interests									0	0	0
Total comprehensive income attributable to partners									299	230	88
Reportable Legal Entities \| Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Net income									298	229	88
Other comprehensive income (loss):
Reclassification of cash flow hedge losses into earnings									1	1
Other comprehensive income from consolidated subsidiaries									0	0
Total other comprehensive income									1	1	0
Total comprehensive income									299	230	88
Total comprehensive income attributable to noncontrolling interests									0	0	0
Total comprehensive income attributable to partners									299	230	88
Reportable Legal Entities \| Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income									589	523	415
Other comprehensive income (loss):
Reclassification of cash flow hedge losses into earnings									0	0
Other comprehensive income from consolidated subsidiaries									0	0
Total other comprehensive income									0	0	0
Total comprehensive income									589	523	415
Total comprehensive income attributable to noncontrolling interests									(4)	(5)	(6)
Total comprehensive income attributable to partners									585	518	409
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Net income									(883)	(747)	(497)
Other comprehensive income (loss):
Reclassification of cash flow hedge losses into earnings									0	0
Other comprehensive income from consolidated subsidiaries									(1)	(1)
Total other comprehensive income									(1)	(1)	0
Total comprehensive income									(884)	(748)	(497)
Total comprehensive income attributable to noncontrolling interests									0	0	0
Total comprehensive income attributable to partners									$ (884)	$ (748)	$ (497)

Condensed Consolidating Financial Information - Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	$ 662	$ 896	$ 645
INVESTING ACTIVITIES:
Intercompany transfers	0	0	0
Capital expenditures	(595)	(375)	(144)
Investments in unconsolidated affiliates, net	(354)	(148)	(53)
Proceeds from sale of assets	4	132	163
Net cash used in investing activities	(945)	(391)	(34)
FINANCING ACTIVITIES:
Intercompany transfers	0	0	0
Proceeds from debt	5,161	116	3,353
Payments of debt	(4,560)	(811)	(3,628)
Excess Purchase Price Of Acquired Assets And Commodity Hedge		(487)
Costs incurred to redeem senior notes	(18)	0	0
Proceeds from Issuance of Preferred Limited Partners Units	261	487	0
Distributions to preferred limited partners	(46)	0	0
Net change in advances to predecessor from DCP Midstream, LLC	0	418	157
Distributions to limited partners and general partner	(658)	(545)	(483)
Distributions to noncontrolling interests	(5)	(7)	(7)
Other	(7)	(8)	(5)
Net cash provided by (used in) financing activities	128	(350)	(613)
Net change in cash and cash equivalents	(155)	155	(2)
Cash and cash equivalents, beginning of period	156	1	3
Cash and cash equivalents, end of period	1	156	1
Parent Guarantor
FINANCING ACTIVITIES:
Excess Purchase Price Of Acquired Assets And Commodity Hedge		(487)
Costs incurred to redeem senior notes	0
Subsidiary Issuer
FINANCING ACTIVITIES:
Excess Purchase Price Of Acquired Assets And Commodity Hedge		0
Costs incurred to redeem senior notes	(18)
Non-Guarantor Subsidiaries
FINANCING ACTIVITIES:
Excess Purchase Price Of Acquired Assets And Commodity Hedge		0
Costs incurred to redeem senior notes	0
Reportable Legal Entities \| Parent Guarantor
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	0	0	0
INVESTING ACTIVITIES:
Intercompany transfers	443	58	483
Capital expenditures	0	0	0
Investments in unconsolidated affiliates, net	0	0	0
Proceeds from sale of assets	0	0	0
Net cash used in investing activities	443	58	483
FINANCING ACTIVITIES:
Intercompany transfers	0	0	0
Proceeds from debt	0	0	0
Payments of debt	0	0	0
Proceeds from Issuance of Preferred Limited Partners Units	261
Distributions to preferred limited partners	(46)
Net change in advances to predecessor from DCP Midstream, LLC		0	0
Distributions to limited partners and general partner	(658)	(545)	(483)
Distributions to noncontrolling interests	0	0	0
Other	0	0	0
Net cash provided by (used in) financing activities	(443)	(58)	(483)
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of period	0	0	0
Cash and cash equivalents, end of period	0	0	0
Reportable Legal Entities \| Subsidiary Issuer
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	(263)	(283)	(305)
INVESTING ACTIVITIES:
Intercompany transfers	(269)	1,141	585
Capital expenditures	0	0	0
Investments in unconsolidated affiliates, net	0	0	0
Proceeds from sale of assets	0	0	0
Net cash used in investing activities	(269)	1,141	585
FINANCING ACTIVITIES:
Intercompany transfers	0	0	0
Proceeds from debt	4,961	116	3,353
Payments of debt	(4,560)	(811)	(3,628)
Proceeds from Issuance of Preferred Limited Partners Units	0
Distributions to preferred limited partners	0
Net change in advances to predecessor from DCP Midstream, LLC		0	0
Distributions to limited partners and general partner	0	0	0
Distributions to noncontrolling interests	0	0	0
Other	(6)	(8)	(5)
Net cash provided by (used in) financing activities	377	(703)	(280)
Net change in cash and cash equivalents	(155)	155	0
Cash and cash equivalents, beginning of period	155	0	0
Cash and cash equivalents, end of period	0	155	0
Reportable Legal Entities \| Non-Guarantor Subsidiaries
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	925	1,179	950
INVESTING ACTIVITIES:
Intercompany transfers	0	0	0
Capital expenditures	(595)	(375)	(144)
Investments in unconsolidated affiliates, net	(354)	(148)	(53)
Proceeds from sale of assets	4	132	163
Net cash used in investing activities	(945)	(391)	(34)
FINANCING ACTIVITIES:
Intercompany transfers	(174)	(1,199)	(1,068)
Proceeds from debt	200	0	0
Payments of debt	0	0	0
Proceeds from Issuance of Preferred Limited Partners Units	0
Distributions to preferred limited partners	0
Net change in advances to predecessor from DCP Midstream, LLC		418	157
Distributions to limited partners and general partner	0	0	0
Distributions to noncontrolling interests	(5)	(7)	(7)
Other	(1)	0	0
Net cash provided by (used in) financing activities	20	(788)	(918)
Net change in cash and cash equivalents	0	0	(2)
Cash and cash equivalents, beginning of period	1	1	3
Cash and cash equivalents, end of period	1	1	1
Consolidating Adjustments
OPERATING ACTIVITIES
Net cash (used in) provided by operating activities	0	0	0
INVESTING ACTIVITIES:
Intercompany transfers	(174)	(1,199)	(1,068)
Capital expenditures	0	0	0
Investments in unconsolidated affiliates, net	0	0	0
Proceeds from sale of assets	0	0	0
Net cash used in investing activities	(174)	(1,199)	(1,068)
FINANCING ACTIVITIES:
Intercompany transfers	174	1,199	1,068
Proceeds from debt	0	0	0
Payments of debt	0	0	0
Excess Purchase Price Of Acquired Assets And Commodity Hedge		0
Costs incurred to redeem senior notes	0
Proceeds from Issuance of Preferred Limited Partners Units	0
Distributions to preferred limited partners	0
Net change in advances to predecessor from DCP Midstream, LLC		0	0
Distributions to limited partners and general partner	0	0	0
Distributions to noncontrolling interests	0	0	0
Other	0	0	0
Net cash provided by (used in) financing activities	174	1,199	1,068
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of period	0	0	0
Cash and cash equivalents, end of period	$ 0	$ 0	$ 0

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Apr. 15, 2019	Apr. 01, 2019	Mar. 15, 2019	Mar. 01, 2019	Feb. 14, 2019	Feb. 04, 2019	Jan. 30, 2019	Jan. 23, 2019	Jan. 18, 2019	Dec. 17, 2018	Sep. 17, 2018	Jul. 17, 2018
Series B Preferred Limited Partners [Member]
Subsequent Event [Line Items]
Preferred Limited Partnership Unit; Distribution Amount Declared										$ 0.4922	$ 0.6781
Senior Notes Issued July 2018, interest at 5.375% payable semiannually, due July 2025 \| Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Face Amount												$ 500
Proceeds from Issuance of Senior Long-term Debt												$ 495
Debt Instrument, Interest Rate, Stated Percentage												5.375%
Subsequent Event [Member]
Subsequent Event [Line Items]
Distribution Made to Limited Partner, Declaration Date								Jan. 23, 2019
Distribution Made to Limited Partner, Distributions Declared, Per Unit								$ 0.78
Distribution Made to Limited Partner, Distribution Date					Feb. 14, 2019
Distribution Made to Limited Partner, Date of Record						Feb. 04, 2019
Subsequent Event [Member] \| Gas Supply Resources
Subsequent Event [Line Items]
Proceeds from Divestiture of Businesses							$ 90
Loss on Disposition of Business							$ 8
Subsequent Event [Member] \| Series B Preferred Limited Partners [Member]
Subsequent Event [Line Items]
Preferred Limited Partnership Distribution: Declaration Date								Jan. 23, 2019
Preferred Limited Partnership Unit; Distribution Amount Declared								$ 0.4922
Preferred Limited Partnership Distribution; Distribution Date			Mar. 15, 2019
Preferred Limited Partner Distribution: Record Date				Mar. 01, 2019
Subsequent Event [Member] \| Series C Preferred Limited Partners [Member]
Subsequent Event [Line Items]
Preferred Limited Partnership Distribution: Declaration Date								Jan. 23, 2019
Preferred Limited Partnership Unit; Distribution Amount Declared								$ 0.4969
Preferred Limited Partnership Distribution; Distribution Date	Apr. 15, 2019
Preferred Limited Partner Distribution: Record Date		Apr. 01, 2019
Subsequent Event [Member] \| Senior Notes Issued July 2018, interest at 5.375% payable semiannually, due July 2025 \| Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Face Amount									$ 825
Proceeds from Issuance of Senior Long-term Debt									324
Subsequent Event [Member] \| Senior Notes Issued July 2018, interest at 5.375% payable semiannually, due July 2025 \| Outstanding Debt [Member] \| Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Face Amount									500
Subsequent Event [Member] \| Senior Notes Issued July 2018, interest at 5.375% payable semiannually, due July 2025 \| Add-On Debt [Member] \| Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Face Amount									$ 325
Debt Instrument, Interest Rate, Stated Percentage									5.375%

Restructuring (Notes)	12 Months Ended
Restructuring (Notes)	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	20. Restructuring Costs In April 2016, we announced an approximate 10 percent headcount reduction, which involved the elimination of certain operational and corporate positions, as part of ongoing effort to create efficiencies, reduce costs and transform our business. As a result of this headcount reduction, we recorded one-time employee termination costs of approximately $13 million, which are included in restructuring costs in our consolidated statements of operations for the year ended December 31, 2016.