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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		$ 140,647	$ 144,319	$ 152,419	$ 146,922
Allowance for Loan and Lease Losses, Write-offs		(6,018)	(741)	(30,600)	(1,992)
Recoveries			736	1,000	1,383
Provision for credit losses		5,500	3,000	17,750	1,000
Ending balance	[1]	140,569	147,313	140,569	147,313
Allowance for Loan and Lease Loss, Recovery of Bad Debts		440
Provision for Loan and Lease Losses		5,500
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		15,142	14,107	27,559	14,402
Allowance for Loan and Lease Losses, Write-offs		0	0	(23,471)	0
Recoveries			2	132	44
Provision for credit losses			6,060	12,714	5,723
Ending balance	[1]	16,934	20,169	16,934	20,169
Allowance for Loan and Lease Loss, Recovery of Bad Debts		111
Provision for Loan and Lease Losses		1,681
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		78,396	83,456	77,799	83,486
Allowance for Loan and Lease Losses, Write-offs		(5,072)	(62)	(5,072)	(62)
Recoveries			330	0	333
Provision for credit losses			(3,688)	1,675	(3,721)
Ending balance	[1]	74,402	80,036	74,402	80,036
Allowance for Loan and Lease Loss, Recovery of Bad Debts		0
Provision for Loan and Lease Losses		1,078
Construction Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		9,038	11,710	10,762	12,316
Allowance for Loan and Lease Losses, Write-offs		0	0	0	0
Recoveries			0	0	0
Provision for credit losses			(291)	(1,932)	(897)
Ending balance	[1]	8,830	11,419	8,830	11,419
Allowance for Loan and Lease Loss, Recovery of Bad Debts		0
Provision for Loan and Lease Losses		(208)
Small Business [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		3,606	2,784	2,834	3,508
Allowance for Loan and Lease Losses, Write-offs		(112)	0	(199)	(59)
Recoveries			88	74	147
Provision for credit losses			(248)	1,205	(972)
Ending balance	[1]	3,914	2,624	3,914	2,624
Allowance for Loan and Lease Loss, Recovery of Bad Debts		35
Provision for Loan and Lease Losses		385
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		21,465	19,750	20,973	14,484
Allowance for Loan and Lease Losses, Write-offs		0	0	0	0
Recoveries			0	0	0
Provision for credit losses			852	2,174	6,118
Ending balance	[1]	23,147	20,602	23,147	20,602
Allowance for Loan and Lease Loss, Recovery of Bad Debts		0
Provision for Loan and Lease Losses		1,682
Home Equity Loan [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		12,433	11,740	11,504	17,986
Allowance for Loan and Lease Losses, Write-offs		0	0	0	(122)
Recoveries			65	38	105
Provision for credit losses			(154)	1,004	(6,318)
Ending balance	[1]	12,546	11,651	12,546	11,651
Allowance for Loan and Lease Loss, Recovery of Bad Debts		12
Provision for Loan and Lease Losses		101
Consumer - Other [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		567	772	988	740
Allowance for Loan and Lease Losses, Write-offs		(834)	(679)	(1,858)	(1,749)
Recoveries			251	756	754
Provision for credit losses			469	910	1,067
Ending balance	[1]	796	$ 812	$ 796	$ 812
Allowance for Loan and Lease Loss, Recovery of Bad Debts		282
Provision for Loan and Lease Losses		$ 781

[1] Balances of accrued interest receivable excluded from amortized cost and the calculation of allowance for credit losses amounted to $58.1 million and $42.7 million as of September 30, 2023 and September 30, 2022, respectively.