Changes in Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Beginning Balance	$ 61	$ 63	$ 59
Additions based on tax positions related to the current year	6	8	6
Additions for tax positions for prior years	0	0	9
Reductions for tax positions for prior years	(8)	(6)	(10)
Settlements	(4)	(3)	0
Statute of limitations	(1)	(1)	(1)
Ending Balance	$ 54	$ 61	$ 63