Allowance for Credit Losses (Summary of the Post-Modification Balance of Loans Restructured) (Detail) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($) contract	Sep. 30, 2021 USD ($) contract	Sep. 30, 2022 USD ($) contract	Sep. 30, 2021 USD ($) contract	Sep. 30, 2022 USD ($) contract	Sep. 30, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	7	9	36	45	56	66
TDRs, balance | $	$ 708	$ 559	$ 6,226	$ 6,884	$ 13,212	$ 12,345
Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	7	8	34	43
TDRs, balance | $	$ 708	$ 442	$ 5,334	$ 6,224
Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	3	2	22	15
TDRs, balance | $	$ 435	$ 202	$ 4,265	$ 2,764
Modification to Interest-only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	4	1
TDRs, balance | $	$ 0	$ 0	$ 2,154	$ 113
Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	0	0
TDRs, balance | $	$ 0	$ 0	$ 0	$ 0
Commercial, industrial and other | Commercial, industrial and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	1	5	6	15	10
TDRs, balance | $	$ 0	$ 1	$ 468	$ 547	$ 4,995	$ 2,863
Commercial, industrial and other | Commercial, industrial and other | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	1	4	6
TDRs, balance | $	$ 0	$ 1	$ 305	$ 547
Commercial, industrial and other | Commercial, industrial and other | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	1	0
TDRs, balance | $	$ 0	$ 0	$ 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	0	0	2	0
TDRs, balance | $	$ 0	$ 0	$ 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	0	0
TDRs, balance | $	$ 0	$ 0	$ 0	$ 0
Commercial real estate | Non-construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	2	5	2	6
TDRs, balance | $	$ 0	$ 0	$ 1,907	$ 2,944	$ 1,907	$ 3,045
Commercial real estate | Non-construction | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	1	4
TDRs, balance | $	$ 0	$ 0	$ 1,178	$ 2,401
Commercial real estate | Non-construction | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	1	2
TDRs, balance | $	$ 0	$ 0	$ 1,178	$ 656
Commercial real estate | Non-construction | Modification to Interest-only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	2	1
TDRs, balance | $	$ 0	$ 0	$ 1,907	$ 113
Commercial real estate | Non-construction | Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	0	0
TDRs, balance | $	$ 0	$ 0	$ 0	$ 0
Residential real estate and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	7	8	29	34	39	50
TDRs, balance | $	$ 708	$ 558	$ 3,851	$ 3,393	$ 6,310	$ 6,437
Residential real estate and other | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	7	7	29	33
TDRs, balance | $	$ 708	$ 441	$ 3,851	$ 3,276
Residential real estate and other | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	3	2	20	13
TDRs, balance | $	$ 435	$ 202	$ 3,002	$ 2,108
Residential real estate and other | Modification to Interest-only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	0	0
TDRs, balance | $	$ 0	$ 0	$ 0	$ 0
Residential real estate and other | Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0	0	0
TDRs, balance | $	$ 0	$ 0	$ 0	$ 0