Loans, Allowance for Credit Losses and Credit Quality Textual (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Days To Be Termed As Non Accrual Loans			90 days
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) by percentage	(4.80%)
Provision for credit losses	$ (5,000,000)	$ 20,000,000	$ (7,500,000)	$ 45,000,000
Interest Receivable	29,900,000	32,900,000	29,900,000	32,900,000
Off-Balance Sheet, Credit Loss, Liability	1,200,000		1,200,000
Loans with active Deferrals	233,800,000		233,800,000		$ 173,600,000
Allowance for Loan and Lease Losses, Write-offs	(481,000)
Financing Receivable, Troubled Debt Restructuring, Increase (Decrease) from Modification				2,812,000
us-gaap_FinancingReceivableTroubledDebtRestructuringIncreaseDecreaseFromModification	14,300,000	510,000		1,400,000
Financing Receivable, after Allowance for Credit Loss	1,443,866,000	1,643,596,000	1,443,866,000	1,643,596,000
Loans with active Deferrals	233,800,000		233,800,000		173,600,000
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method				(1,137,000)
Interest Receivable	29,900,000	32,900,000	29,900,000	32,900,000
Loans and Leases Receivable, Allowance	(102,357,000)	(112,176,000)	(102,357,000)	(112,176,000)	(113,392,000)
Off-Balance Sheet, Credit Loss, Liability	1,200,000		1,200,000
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	5,200,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	0	0	0	0
US Government Insured Loan Program [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, before Allowance for Credit Loss	370,500,000	793,000,000.0	370,500,000	793,000,000.0	112,200,000
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for credit losses		4,009,000	(680,000)	9,957,000
Financing Receivable, before Allowance for Credit Loss	1,726,498,000		1,726,498,000		$ 2,103,152,000
Allowance for Loan and Lease Losses, Write-offs	(142,000)
Financing Receivable, after Allowance for Credit Loss	575,392,000	915,434,000	575,392,000	915,434,000
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method				(1,984,000)
Loans and Leases Receivable, Allowance	(17,032,000)	(25,662,000)	(17,032,000)	(25,662,000)
Commercial And Industrial [Member] | Definite Weakness Loss Unlikely [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, after Allowance for Credit Loss	18,026,000	$ 2,124,000	18,026,000	$ 2,124,000
Loans Insured or Guaranteed by US Government Authorities
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 482,700,000		$ 482,700,000