Commitments and Contingencies - Off-Balance-Sheet Originate Loans and Letters of Credit (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Commitments	$ 3,112
Total loan commitments
Loss Contingencies [Line Items]
Commitments	2,821	$ 2,500
Commercial, performance stand-by, and financial stand-by letters of credit
Loss Contingencies [Line Items]
Commitments	291	$ 376
Multi-family and commercial real estate
Loss Contingencies [Line Items]
Commitments	520
Multi-family and commercial real estate | Multifamily And Commercial Real Estate Loans
Loss Contingencies [Line Items]
Commitments	352
Multi-family and commercial real estate | Acquisition, Development, and Construction
Loss Contingencies [Line Items]
Commitments	168
Other loan commitments
Loss Contingencies [Line Items]
Commitments	$ 2,301