Federal, State and Local Taxes - Reconciliation of Statutory Federal Income Tax Expense (Benefit) Reported in Net Income to Combined Actual Income Tax Expense (Benefit) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Statutory federal income tax at 21%, 21% and 21%, respectively	$ 169	$ 123	$ 110
State and local income taxes, net of federal income tax effect	40	27	18
Effect of tax law changes		(73)
Non-deductible FDIC deposit insurance premiums	9	8	7
Effect of tax deductibility of ESOP	(3)	(3)	(3)
Non-taxable income and expense of BOLI	(6)	(7)	(6)
Non-deductible merger expense	3
Federal tax credits		(1)	(1)
Adjustments relating to prior tax years	(1)	1
Other, net	(1)	2	3
Income tax expense reported in net income	$ 210	$ 77	$ 128