Employee Benefits - Retirement Plan, Based on Measurement Date (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in Plan Assets:
Fair value of assets at end of year	$ 283
Pension Benefits
Change in Benefit Obligation:
Benefit obligation at beginning of year	172	$ 160
Interest cost	4	5	$ 6
Actuarial loss (gain)	(9)	15
Annuity payments	(6)	(7)
Settlements	(3)	(1)
Benefit obligation at end of year	158	172	160
Change in Plan Assets:
Fair value of assets at beginning of year	261	243
Actual return (loss) on plan assets	31	26
Annuity payments	(6)	(7)
Settlements	(3)	(1)
Fair value of assets at end of year	283	261	$ 243
Funded status (included in “Other assets”)	125	89
Changes recognized in other comprehensive income for the year ended December 31:
Amortization of actuarial loss	(7)	(7)
Net actuarial (gain) loss arising during the year	(23)	4
Total recognized in other comprehensive income for the year (pre-tax)	(30)	(3)
Accumulated other comprehensive loss (pre-tax) not yet recognized in net periodic benefit cost at December 31:
Actuarial loss, net	43	73
Total accumulated other comprehensive loss (pre-tax)	$ 43	$ 73