Income Taxes - Difference Between Effective Tax Rate (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax provision (benefit) at federal statutory rate	$ (90)	$ (19)	$ 12
Foreign tax rate differential	1	2	2
State income tax provision (benefit), net of federal benefit	(4)		3
Nondeductible expenses	2	3	9
Foreign tax credits		1	21
Benefit of net operating loss			(14)
One-time transition tax			1
Investment in subsidiaries		(9)
Nondeductible goodwill impairment	25	16
Change in valuation allowance	61	9	(28)
Change in contingency reserve and other	2	1
Income tax provision (benefit)	$ (3)	$ 4	$ 6
Effective tax rate	0.60%	(4.40%)	10.70%