Loans, Allowance for Credit Losses and Credit Quality - Financing Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2025		Sep. 30, 2024		Sep. 30, 2025		Sep. 30, 2024		Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 144,773		$ 150,859		$ 169,984		$ 142,222		$ 142,222
Allowance for Loan and Lease Losses, Write-offs	(2,670)		(7,006)		(51,036)		(8,695)		(10,347)	[1]
Allowance for Loan and Lease Loss, Recovery of Bad Debts	834		343		1,789		1,419
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	(9,020)				(9,020)
Ending balance	190,476	[2]	163,696	[2]	190,476	[2]	163,696	[2]	169,984
Provision for Loan and Lease Losses	38,519		19,500		60,719		28,750
Accounts Receivable, Noncurrent, Accrued Interest, Writeoff	173		95		741		594
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	38,451		38,393		30,799		36,049		36,049
Allowance for Loan and Lease Losses, Write-offs	(1,196)		(6,049)		(4,208)		(6,218)		(6,593)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	18		6		85		144
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	(4,016)				(4,016)
Ending balance	54,482	[2]	32,205	[2]	54,482	[2]	32,205	[2]	30,799
Provision for Loan and Lease Losses	13,193		(145)		23,790		2,230
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	60,927		67,051		93,718		61,305		61,305
Allowance for Loan and Lease Losses, Write-offs	(40)		0		(43,384)		0		0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	19		0		20		0
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	(2,796)				(2,796)
Ending balance	77,083	[2]	87,459	[2]	77,083	[2]	87,459	[2]	93,718
Provision for Loan and Lease Losses	13,381		20,408		23,933		26,154
Construction Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	8,183		7,804		8,166		7,683		7,683
Allowance for Loan and Lease Losses, Write-offs	0		0		0		0		0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0		0		0		0
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	(1,739)				(1,739)
Ending balance	15,933	[2]	7,526	[2]	15,933	[2]	7,526	[2]	8,166
Provision for Loan and Lease Losses	6,011		(278)		6,028		(157)
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	25,414		24,836		25,238		23,637		23,637
Allowance for Loan and Lease Losses, Write-offs	0		0		0		0		0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0		0		0		0
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	(297)				(297)
Ending balance	29,890	[2]	24,503	[2]	29,890	[2]	24,503	[2]	25,238
Provision for Loan and Lease Losses	4,179		(333)		4,355		866
Home Equity Loan [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	10,911		11,755		11,007		12,797		12,797
Allowance for Loan and Lease Losses, Write-offs	0		(38)		(96)		(49)		(380)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	12		14		79		295
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	(118)				(118)
Ending balance	12,187	[2]	11,161	[2]	12,187	[2]	11,161	[2]	11,007
Provision for Loan and Lease Losses	1,146		(570)		1,079		(1,882)
Consumer - Other [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	887		1,020		1,056		751		751
Allowance for Loan and Lease Losses, Write-offs	(1,434)		(919)		(3,348)		(2,428)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	785		323		1,605		980
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	(54)				(54)
Ending balance	901	[2]	842	[2]	901	[2]	842	[2]	$ 1,056
Provision for Loan and Lease Losses	$ 609		$ 418		$ 1,534		$ 1,539

[1] (2)Loan origination dates in the tables above reflect the original origination date, or the date of a material modification of a previously originated loan.

[2] Balances of accrued interest receivable excluded from amortized cost and the calculation of allowance for credit losses amounted to $70.8 million and $55.3 million as of September 30, 2025 and September 30, 2024, respectively.