Provision (Benefit) for Income Taxes - Provision (Benefit) for Income Taxes from Continuing Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ (19)	$ (38)	$ (18)
State	(1)	1	1
Total current	(20)	(37)	(17)
Deferred:
Federal	81	107	(100)
State	9	4	(11)
Total Deferred	90	111	(111)
Total provision (benefit)	$ 70	$ 74	$ (128)