Equity Method Investments - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
Schedule of Equity Method Investments [Line Items]
Unamortized basis differences included in equity investments	$ 39,000,000			$ 40,000,000
Amortization expense (income)	1,000,000	$ 1,000,000
Equity method investments	814,000,000			823,000,000
Cumulative effect to total (deficit)/equity			$ 9,000,000		$ 2,000,000
Permian Basin
Schedule of Equity Method Investments [Line Items]
Capital contribution	5,000,000
Accounting Standards Update 2016-01
Schedule of Equity Method Investments [Line Items]
Cumulative effect to total (deficit)/equity			9,000,000		7,000,000
Poseidon
Schedule of Equity Method Investments [Line Items]
Equity method investments	0	0		$ 0
Investment, excess distribution	$ 8,000,000	$ 1,000,000
Poseidon | Accounting Standards Update 2016-01
Schedule of Equity Method Investments [Line Items]
Cumulative effect to total (deficit)/equity			$ 0		$ 0