Loans, Allowance for Credit Losses and Credit Quality Troubled Debt Restructurings (Details) $ in Thousands		3 Months Ended	6 Months Ended
		Jun. 30, 2021 USD ($) contract	Jun. 30, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		1	8
Financing Receivable, Troubled Debt Restructuring, Premodification	[1]	$ 89	$ 18,301
Financing Receivable, Troubled Debt Restructuring, Postmodification	[1]	$ 89	$ 18,301
Commercial And Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		0	1
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 0	$ 14,148
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 0	$ 14,148
Commercial Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		0	5
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 0	$ 3,964
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 0	$ 3,964
Small Business [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		1	2
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 89	$ 189
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 89	$ 189

[1] The pre-modification and post-modification balances represent the legal principal balance of the loan. Activity presented in the table above includes $14.3 million of modifications on existing TDR's occurring during the six months ended June 30, 2021.