Equity Method Investments - Summarized Financial Information (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Revenues and other income	$ 754			$ 1,345			$ 2,256	$ 3,975
Income (loss) from operations	(242)			237			(930)	563
Net income (loss)	(317)	$ (750)	$ (46)	165	$ 161	$ 174	(1,113)	500
Consolidated Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Revenues and other income	140			184			423	637
Income (loss) from operations	19			61			(21)	192
Net income (loss)	$ 12			$ 45			$ (27)	$ 140