Allowance for Credit Losses (Summary of Loans Restructured and Subsequently Defaulted Under the Restructured Terms) (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
Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	13	6	14	9
TDRs, balance | $	$ 5,067	$ 2,590	$ 5,308	$ 3,915
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 | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	10	1	11	4
TDRs, balance | $	$ 4,469	$ 199	$ 4,710	$ 1,524
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 | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	3	0	3
TDRs, balance | $	$ 0	$ 2,275	$ 0	$ 2,275
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 | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	3	2	3	2
TDRs, balance | $	$ 598	$ 116	$ 598	$ 116