Loans, Allowance for Credit Losses and Credit Quality Financing Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 115,625	$ 115,625	$ 112,176	$ 67,740
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		(1,137)
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		1,157
Allowance for Loan and Lease Losses, Write-offs	(4,304)	(5,748)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	253	1,113
Provision for Loan and Lease Losses	7,500	52,500
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	28,219	28,219	25,662	17,594
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		(1,984)
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		49
Allowance for Loan and Lease Losses, Write-offs	(185)	(185)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1	47
Provision for Loan and Lease Losses	2,741	12,698
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	39,386	39,386	36,956	32,935
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		(13,048)
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		337
Allowance for Loan and Lease Losses, Write-offs	(3,885)	(3,885)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	9	9
Provision for Loan and Lease Losses	6,306	23,038
Construction Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	5,210	5,210	4,501	6,053
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		(3,652)
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		0
Allowance for Loan and Lease Losses, Write-offs	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0	0
Provision for Loan and Lease Losses	709	2,809
Small Business [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	4,593	4,593	4,561	1,746
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		495
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		0
Allowance for Loan and Lease Losses, Write-offs	(49)	(194)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	2	8
Provision for Loan and Lease Losses	79	2,538
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	14,163	14,163	15,046	3,440
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		9,828
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		423
Allowance for Loan and Lease Losses, Write-offs	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1	2
Provision for Loan and Lease Losses	(884)	470
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	23,572	23,572	24,860	5,576
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		7,012
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		319
Allowance for Loan and Lease Losses, Write-offs	0	(142)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	21	174
Provision for Loan and Lease Losses	(1,309)	10,633
Consumer - Other [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	482	482	$ 590	$ 396
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		212
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		29
Allowance for Loan and Lease Losses, Write-offs	(185)	(1,342)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	219	873
Provision for Loan and Lease Losses	$ (142)	$ 314

Amount of increase in allowance for credit loss on financing receivable purchased with credit deterioration.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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The effect of a change in method or methods for calculating the allowance for credit losses on the current period provision.

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Amount of increase in allowance for credit loss on financing receivable from recovery.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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