Income Taxes - Income (Loss) Before Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
United States - Income (Loss) Before Income Taxes	$ (1,509)	$ (338)	$ (219)
Foreign - Income (Loss) Before Income Taxes	(1,341)	559	439
Income (Loss) Before Income Taxes	$ (2,850)	$ 221	$ 220