Loans, Allowance for Credit Losses and Credit Quality Finance Receivable, Nonaccrual (Details) - USD ($) $ in Thousands	Jun. 30, 2021		Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance	$ 26,618		$ 31,332
Financing Receivable, Nonaccrual, No Allowance	21,200		35,528
Tdrs Recorded Investment On Nonaccrual Status	20,212		22,209
Financing Receivable Recorded Investment Trouble Debt Restructuring	39,707		39,192
Additional Commitments To Lend To Borrower For Trouble Debt Restructuring	412		263
Financing Receivable, Nonaccrual	47,818	[1]	66,860
Tdrs Recorded Investment On Accrual Status	19,495		16,983
Commercial And Industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance	3,465		3,804
Financing Receivable, Nonaccrual, No Allowance	17,366		30,925
Financing Receivable, Nonaccrual	20,831		34,729
Commercial Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance	9,031		10,195
Financing Receivable, Nonaccrual, No Allowance	0		0
Financing Receivable, Nonaccrual	9,031		10,195
Small Business [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance	558		815
Financing Receivable, Nonaccrual, No Allowance	0		10
Financing Receivable, Nonaccrual	558		825
Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance	8,952		10,935
Financing Receivable, Nonaccrual, No Allowance	3,834		4,593
Financing Receivable, Nonaccrual	12,786		15,528
Home Equity Line of Credit [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance	4,517		5,427
Financing Receivable, Nonaccrual, No Allowance	0		0
Financing Receivable, Nonaccrual	4,517		5,427
Consumer - Other [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance	95		156
Financing Receivable, Nonaccrual, No Allowance	0		0
Financing Receivable, Nonaccrual	$ 95		$ 156

[1] Included in these amounts were $20.2 million and $22.2 million of nonaccruing TDRs at June 30, 2021 and December 31, 2020, respectively.