Loans and the Allowance for Credit Losses - Recorded Investment in Non-Accrual Loans and TDRs (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Impaired [Line Items]
Non-accrual loans	$ 31,714	$ 35,742
TDRs	5,699	5,293
Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	3,579	3,746
Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	2,120	1,547
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	4,275	5,064
TDRs	183	192
Commercial and Industrial [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	183	192
Home Equity [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	4,909	5,163
TDRs	487	535
Home Equity [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	254	277
Home Equity [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	233	258
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	7,043	7,788
TDRs	627	507
Commercial Real Estate [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	414	374
Commercial Real Estate [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	213	133
Commercial Real Estate [Member] | Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans		73
TDRs	53
Commercial Real Estate [Member] | Commercial Real Estate - Land and Construction [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	53
Commercial Real Estate [Member] | Commercial Real Estate - Improved Property [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	7,043	7,715
TDRs	574	507
Commercial Real Estate [Member] | Commercial Real Estate - Improved Property [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	361	374
Commercial Real Estate [Member] | Commercial Real Estate - Improved Property [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	213	133
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	15,111	17,190
TDRs	4,372	4,031
Residential Real Estate [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	2,698	2,875
Residential Real Estate [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	1,674	1,156
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	376	537
TDRs	30	28
Consumer [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	$ 30	$ 28