Loans, Allowance for Credit Losses and Credit Quality Schedule of Debtor Troubled Debt Restructurings, Subsequent Period (Details) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2021 USD ($) contract	Sep. 30, 2020 USD ($) contract		Sep. 30, 2021 USD ($) contract		Sep. 30, 2020 USD ($) contract
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		0	5		8		17
Financing Receivable, Troubled Debt Restructuring, Premodification	[1]		$ 827		$ 18,301		$ 3,580
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 0	$ 827	[1]	$ 18,301	[1]	$ 3,639	[1]
Commercial And Industrial [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		0	2		1		5
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 0	$ 83		$ 14,148		$ 391
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 0	$ 83		$ 14,148		$ 391
Commercial Real Estate [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		0	3		5		8
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 0	$ 744		$ 3,964		$ 2,518
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 0	$ 744		$ 3,964		$ 2,518
Small Business [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		0	0		2		2
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 0	$ 0		$ 189		$ 112
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 0	$ 0		$ 189		$ 88
Residential Real Estate [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract			0				2
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 0				$ 559
Financing Receivable, Troubled Debt Restructuring, Postmodification			$ 0				$ 642

[1] The pre-modification and post-modification balances represent the legal principal balance of the loan. Activity presented in the tables above includes no modifications on existing TDRs during the three months ended September 30, 2021, $14.3 million of modifications on existing TDRs during the nine months ended September 30, 2021, and $83,000 and $1.5 million of modifications on existing TDRs during the three and nine months ended September 30, 2020, respectively.