Income Taxes - Income Before Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. income (loss) before tax	$ (267)	$ 867	$ 881
Foreign income (loss) before tax	(657)	377	197
Income (loss) before income taxes	$ (924)	$ 1,244	$ 1,078