Unconsolidated Investments - Summarized Operating Results of Unconsolidated Investees (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Revenue	$ 47	$ 65	$ 208	$ 245
Cost of revenue	30	29	98	89
Operating expenses	37	20	117	74
Other expense	23	18	73	58
Net income (loss)	$ (43)	$ (2)	$ (80)	$ 24