Allowance for Credit Losses (Summary of the Post-Modification Balance of Loans Restructured) (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) contract	Mar. 31, 2021 USD ($) contract	Mar. 31, 2022 USD ($) contract	Mar. 31, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	13	20	57	106
TDRs, balance | $	$ 3,097	$ 2,126	$ 14,839	$ 24,201
Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	11	20
TDRs, balance | $	$ 2,206	$ 2,126
Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	9	10
TDRs, balance | $	$ 2,025	$ 1,403
Modification to Interest-only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	4	1
TDRs, balance | $	$ 2,154	$ 113
Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Commercial, industrial and other | Commercial, industrial and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	3	2	17	18
TDRs, balance | $	$ 282	$ 151	$ 5,205	$ 6,910
Commercial, industrial and other | Commercial, industrial and other | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	2	2
TDRs, balance | $	$ 120	$ 151
Commercial, industrial and other | Commercial, industrial and other | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	1	0
TDRs, balance | $	$ 85	$ 0
Commercial, industrial and other | Commercial, industrial and other | Modification to Interest-only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	2	0
TDRs, balance | $	$ 247	$ 0
Commercial, industrial and other | Commercial, industrial and other | Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Commercial real estate | Non-construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	2	2	5	7
TDRs, balance | $	$ 1,907	$ 237	$ 4,613	$ 3,466
Commercial real estate | Non-construction | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	1	2
TDRs, balance | $	$ 1,178	$ 237
Commercial real estate | Non-construction | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	1	1
TDRs, balance | $	$ 1,178	$ 113
Commercial real estate | Non-construction | Modification to Interest-only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	2	1
TDRs, balance | $	$ 1,907	$ 113
Commercial real estate | Non-construction | Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Residential real estate and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	8	16	35	81
TDRs, balance | $	$ 908	$ 1,738	$ 5,021	$ 13,825
Residential real estate and other | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	8	16
TDRs, balance | $	$ 908	$ 1,738
Residential real estate and other | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	7	9
TDRs, balance | $	$ 762	$ 1,290
Residential real estate and other | Modification to Interest-only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Residential real estate and other | Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0