Loans and Allowance for Loan Losses - Summary of TDR Loans on Accrual and Nonaccrual (Detail) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2022 USD ($) loan	Mar. 31, 2022 USD ($) contract	Mar. 31, 2021 contract	Dec. 31, 2021 USD ($) loan
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	250	7	1	249
Balance of Loans	$ 45,653	$ 45,653		$ 47,535
TDRs on Accrual Status | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	191			197
Balance of Loans	$ 32,016	32,016		$ 33,336
TDRs on Non-Accrual Status | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	59			52
Balance of Loans	$ 13,637	13,637		$ 14,199
Commercial and industrial | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	8			7
Balance of Loans	$ 12,275	12,275		$ 13,728
Commercial and industrial | TDRs on Accrual Status | Commercial Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	1			1
Balance of Loans	$ 3,894	3,894		$ 3,745
Commercial and industrial | TDRs on Non-Accrual Status | Commercial Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	7			6
Balance of Loans	$ 8,381	8,381		$ 9,983
Commercial real estate | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	1			1
Balance of Loans	$ 3,520	3,520		$ 3,520
Commercial real estate | TDRs on Accrual Status | Commercial Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	1			1
Balance of Loans	$ 3,520	3,520		$ 3,520
Commercial real estate | TDRs on Non-Accrual Status | Commercial Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	0			0
Balance of Loans	$ 0	$ 0		$ 0
Business Banking | Commercial Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	13	5	0	8
Balance of Loans	$ 4,585	$ 4,585		$ 4,213
Business Banking | TDRs on Accrual Status | Commercial Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	5			5
Balance of Loans	$ 3,771	3,771		$ 3,830
Business Banking | TDRs on Non-Accrual Status | Commercial Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	8			3
Balance of Loans	$ 814	$ 814		$ 383
Residential real estate | Residential Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	145	1	1	148
Balance of Loans	$ 21,369	$ 21,369		$ 22,134
Residential real estate | TDRs on Accrual Status | Residential Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	116			121
Balance of Loans	$ 17,786	17,786		$ 19,119
Residential real estate | TDRs on Non-Accrual Status | Residential Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	29			27
Balance of Loans	$ 3,583	$ 3,583		$ 3,015
Consumer home equity | Consumer Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans	81	1	0	83
Balance of Loans	$ 3,887	$ 3,887		$ 3,922
Consumer home equity | TDRs on Accrual Status | Consumer Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	66			67
Balance of Loans	$ 3,028	3,028		$ 3,104
Consumer home equity | TDRs on Non-Accrual Status | Consumer Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	15			16
Balance of Loans	$ 859	859		$ 818
Other Consumer | Consumer Portfolio Segment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	2			2
Balance of Loans	$ 17	17		$ 18
Other Consumer | TDRs on Accrual Status | Consumer Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	2			2
Balance of Loans	$ 17	17		$ 18
Other Consumer | TDRs on Non-Accrual Status | Consumer Portfolio Segment | Special mention | Contractual Obligation Modification
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Loans | loan	0			0
Balance of Loans	$ 0	$ 0		$ 0