Schedule of Changes in Benefit Obligation (Detail) - Postretirement Benefits Other Than Pensions - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	$ 21	$ 18
Service cost	0	0	$ 0
Interest cost	1	1	1
Actuarial loss (gain)	(1)	2
Benefits paid	0	0
Other	0	0
Benefit obligation at end of year	$ 21	$ 21	$ 18