Income Taxes - Schedule of Domestic and Foreign Income Before Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. (loss) income before tax	$ (1,449)	$ 350	$ 498
Foreign (loss) income before tax	(1)	1	2
(Loss) Income before income taxes	$ (1,450)	$ 351	$ 500