Allowance for Credit Losses - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Maximum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period	150 days
Minimum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period	90 days
Minimum [Member] | Commercial Loans and Commercial Real Estate [Member]
Loans And Leases Receivable [Line Items]
Amount of real estate loan as reported as accruing or nonaccruing	$ 1