Income Taxes - Components of (Benefit) Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
U.S. Federal	$ 1	$ 16	$ 34
State	3	3	6
Foreign	20	11	3
Total current	24	30	43
Deferred:
U.S. Federal	(29)	3	(18)
Foreign	(1)	2	(2)
Total deferred	(30)	5	(20)
Total (benefit) provision for income taxes	$ (6)	$ 35	$ 23