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Investing Activities (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended				9 Months Ended
Investing Activities (Details) - USD ($) $ in Millions	Apr. 30, 2019	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Apr. 10, 2019
Schedule of Equity Method Investments [Line Items]
Impairment of equity-method investments (Note 13)		$ (114)		$ 0		$ (186)	$ 0
Gain (loss) on deconsolidation of businesses		0		0		(2)	62
Gain on disposition of equity-method investments		0		0		122	0
Other investing income (loss) - net		(107)		2		(54)	74
Proceeds from Sale of Equity Method Investments						485	0
West [Member] \| Jackalope Gas Gathering Services LLC [Member]
Schedule of Equity Method Investments [Line Items]
Gain (loss) on deconsolidation of businesses					$ 62
Goodwill, Period Increase (Decrease)					$ 47
Equity Method Investment, Ownership Percentage	50.00%
Jackalope Gas Gathering Services LLC [Member]
Schedule of Equity Method Investments [Line Items]
Gain on disposition of equity-method investments			$ 122
Equity Method Investment, Ownership Percentage								50.00%
Proceeds from Sale of Equity Method Investments	$ 485
Jackalope Gas Gathering Services LLC [Member] \| West [Member]
Schedule of Equity Method Investments [Line Items]
Variable Interest Entity Ownership Percentage					50.00%
Investments, Fair Value Disclosure					$ 310
Measurement Input, Discount Rate [Member] \| Jackalope Gas Gathering Services LLC [Member] \| West [Member]
Schedule of Equity Method Investments [Line Items]
Property Plant And Equipment And Intangibles Fair Value Inputs					10.90%
Other Income [Member]
Schedule of Equity Method Investments [Line Items]
Other investing income (loss) - net		$ 7		$ 2		$ 12	$ 12