Loans, Allowance for Credit Losses and Credit Quality Finance Receivable, Nonaccrual (Details) - USD ($) $ in Thousands		Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance		$ 22,370	$ 31,332
Financing Receivable, Nonaccrual, No Allowance		23,440	35,528
Tdrs Recorded Investment On Nonaccrual Status		21,104	22,209
Financing Receivable Recorded Investment Trouble Debt Restructuring		37,054	39,192
Additional Commitments To Lend To Borrower For Trouble Debt Restructuring		352	263
Financing Receivable, Nonaccrual	[1]	45,810	66,860
Tdrs Recorded Investment On Accrual Status		15,950	16,983
Commercial And Industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance		3,468	3,804
Financing Receivable, Nonaccrual, No Allowance		15,807	30,925
Financing Receivable, Nonaccrual		19,275	34,729
Commercial Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance		8,541	10,195
Financing Receivable, Nonaccrual, No Allowance		3,247	0
Financing Receivable, Nonaccrual		11,788	10,195
Small Business [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance		46	815
Financing Receivable, Nonaccrual, No Allowance		0	10
Financing Receivable, Nonaccrual		46	825
Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance		6,486	10,935
Financing Receivable, Nonaccrual, No Allowance		4,386	4,593
Financing Receivable, Nonaccrual		10,872	15,528
Home Equity Line of Credit [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance		3,746	5,427
Financing Receivable, Nonaccrual, No Allowance		0	0
Financing Receivable, Nonaccrual		3,746	5,427
Consumer - Other [Member]
Financing Receivable, Nonaccrual [Line Items]
Finance Receivable, Nonaccrual, with allowance		83	156
Financing Receivable, Nonaccrual, No Allowance		0	0
Financing Receivable, Nonaccrual		$ 83	$ 156

[1] Included in these amounts were $21.1 million and $22.2 million of nonaccruing TDRs at September 30, 2021 and December 31, 2020, respectively.