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Investments In Unconsolidated Affiliates - Investments In Unconsolidated Affiliates (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 3,696		$ 3,696		$ 3,724
Earnings from unconsolidated affiliates	$ 125	$ 117	$ 201	$ 230
DCP Sand Hills Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	66.67%		66.67%
Investments in unconsolidated affiliates	$ 1,757		$ 1,757		1,764
Earnings from unconsolidated affiliates	$ 70	72	$ 148	140
DCP Southern Hills Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	66.67%		66.67%
Investments in unconsolidated affiliates	$ 741		$ 741		738
Earnings from unconsolidated affiliates	$ 20	22	$ 40	45
Front Range Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	33.33%		33.33%
Investments in unconsolidated affiliates	$ 204		$ 204		206
Earnings from unconsolidated affiliates	$ 9	9	$ 20	16
Gulf Coast Express [Member]
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	25.00%		25.00%
Investments in unconsolidated affiliates	$ 441		$ 441		449
Earnings from unconsolidated affiliates	$ 16	0	$ 32	0
Texas Express Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	10.00%		10.00%
Investments in unconsolidated affiliates	$ 99		$ 99		101
Earnings from unconsolidated affiliates	$ 5	4	$ 9	9
Cheyenne Connector
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	50.00%		50.00%
Investments in unconsolidated affiliates	$ 144		$ 144		83
Mont Belvieu Enterprise Fractionator
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	12.50%		12.50%
Investments in unconsolidated affiliates	$ 27		$ 27		27
Earnings from unconsolidated affiliates	$ 3	3	$ 6	7
Mont Belvieu 1 Fractionator
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	20.00%		20.00%
Investments in unconsolidated affiliates	$ 7		$ 7		9
Earnings from unconsolidated affiliates	$ 3	4	$ 6	8
Discovery Producer Services LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	40.00%		40.00%
Investments in unconsolidated affiliates	$ 251		$ 251		322
Earnings from unconsolidated affiliates	$ 1	3	$ (60)	3
Panola Pipeline Company, LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership investment (as percent)	15.00%		15.00%
Investments in unconsolidated affiliates	$ 21		$ 21		22
Other
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	4		4		$ 3
Earnings from unconsolidated affiliates	$ (2)	$ 0	$ 0	$ 2