Loans and Allowance for Loan Losses - Summary of TDR Loans on Accrual and Nonaccrual (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) loan	Dec. 31, 2021 USD ($) contract	Dec. 31, 2020 USD ($) loan	Dec. 31, 2020 USD ($) contract	Dec. 31, 2019 contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	249	5	301	40	40
Balance of Loans	$ 47,535	$ 47,535	$ 53,204	$ 53,204
Special Mention | Contractual Obligation Modification | TDRs on Accrual Status
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	197		248
Balance of Loans	$ 33,336	$ 33,336	$ 41,095	41,095
Special Mention | Contractual Obligation Modification | TDRs on Non-accrual Status
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans		52	53
Balance of Loans	$ 14,199	$ 14,199	$ 12,109	$ 12,109
Commercial and industrial | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	7	0	8	1	16
Balance of Loans	$ 13,728	$ 13,728	$ 12,447	$ 12,447
Commercial and industrial | Special Mention | Contractual Obligation Modification | TDRs on Accrual Status | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	1		1
Balance of Loans	$ 3,745	3,745	$ 5,628	5,628
Commercial and industrial | Special Mention | Contractual Obligation Modification | TDRs on Non-accrual Status | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	6		7
Balance of Loans	$ 9,983	$ 9,983	$ 6,819	$ 6,819
Commercial real estate | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	1	0	2	1	2
Balance of Loans	$ 3,520	$ 3,520	$ 4,001	$ 4,001
Commercial real estate | Special Mention | Contractual Obligation Modification | TDRs on Accrual Status | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	1		1
Balance of Loans	$ 3,520	3,520	$ 3,521	3,521
Commercial real estate | Special Mention | Contractual Obligation Modification | TDRs on Non-accrual Status | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	0		1
Balance of Loans	$ 0	$ 0	$ 480	$ 480
Business banking | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	8	0	12	6	2
Balance of Loans	$ 4,213	$ 4,213	$ 5,193	$ 5,193
Business banking | Special Mention | Contractual Obligation Modification | TDRs on Accrual Status | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	5		6
Balance of Loans	$ 3,830	3,830	$ 4,471	4,471
Business banking | Special Mention | Contractual Obligation Modification | TDRs on Non-accrual Status | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	3		6
Balance of Loans	$ 383	$ 383	$ 722	$ 722
Residential real estate | Residential Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	148	2	173	6	11
Balance of Loans	$ 22,134	$ 22,134	$ 26,689	$ 26,689
Residential real estate | Special Mention | Contractual Obligation Modification | TDRs on Accrual Status | Residential Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	121		146
Balance of Loans	$ 19,119	19,119	$ 23,416	23,416
Residential real estate | Special Mention | Contractual Obligation Modification | TDRs on Non-accrual Status | Residential Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	27		27
Balance of Loans	$ 3,015	$ 3,015	$ 3,273	$ 3,273
Consumer home equity | Consumer Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	83	3	103	22	9
Balance of Loans	$ 3,922	$ 3,922	$ 4,845	$ 4,845
Consumer home equity | Special Mention | Contractual Obligation Modification | TDRs on Accrual Status | Consumer Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	67		91
Balance of Loans	$ 3,104	3,104	$ 4,030	4,030
Consumer home equity | Special Mention | Contractual Obligation Modification | TDRs on Non-accrual Status | Consumer Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	16		12
Balance of Loans	$ 818	$ 818	$ 815	$ 815
Other consumer | Consumer Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	2	0	3	4	0
Balance of Loans	$ 18	$ 18	$ 29	$ 29
Other consumer | Special Mention | Contractual Obligation Modification | TDRs on Accrual Status | Consumer Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	2		3
Balance of Loans	$ 18	18	$ 29	29
Other consumer | Special Mention | Contractual Obligation Modification | TDRs on Non-accrual Status | Consumer Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	0		0
Balance of Loans	$ 0	$ 0	$ 0	$ 0