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Financial Instruments with Off-Balance-Sheet Risk - Narrative (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Jan. 01, 2020
Loss Contingencies [Line Items]      
Allowance for credit losses on lending-related commitments $ 2.1 $ 2.3  
Lending-related commitments, expense (benefit) $ (0.2) $ (1.1)  
Cumulative Effect, Period of Adoption, Adjustment      
Loss Contingencies [Line Items]      
Allowance for credit losses on lending-related commitments     $ 3.4