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Loans and Allowance for Credit Losses - Schedule of Company's Loan Portfolio as of the Dates Indicated (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Line Items]
Gross loans before unearned discounts and deferred fees, net	$ 23,713,099		$ 23,574,496
Allowance for loan losses	(325,354)	$ (327,892)	(331,841)	$ (232,113)	$ (224,310)	$ (228,952)
Unearned discounts and deferred fees, net	(431,698)		(489,431)
Net loans	22,956,047		22,753,224
Financing receivable, accrued interest, before allowance for credit loss	81,100		81,900
Commercial and industrial \| Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Gross loans before unearned discounts and deferred fees, net	4,690,914		4,324,615
Allowance for loan losses	(63,209)	(59,508)	(65,768)	(54,110)	(46,490)	(41,090)
Commercial real estate \| Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Gross loans before unearned discounts and deferred fees, net	9,390,773		9,529,071
Allowance for loan losses	(172,339)	(178,826)	(164,376)	(105,090)	(106,634)	(116,175)
Commercial construction \| Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Gross loans before unearned discounts and deferred fees, net	544,546		567,597
Allowance for loan losses	(12,251)	(11,123)	(21,058)	(9,326)	(8,514)	(8,462)
Business banking \| Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Gross loans before unearned discounts and deferred fees, net	1,561,530		1,603,489
Allowance for loan losses	(23,171)	(22,159)	(22,921)	(20,685)	(20,315)	(19,899)
Residential real estate \| Residential Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Gross loans before unearned discounts and deferred fees, net	5,442,043		5,516,114
Allowance for loan losses	(40,585)	(42,641)	(44,177)	(31,481)	(31,096)	(32,291)
Consumer home equity \| Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Gross loans before unearned discounts and deferred fees, net	1,824,835		1,758,099
Allowance for loan losses	(10,320)	(9,627)	(9,171)	(7,080)	(6,891)	(7,472)
Other consumer \| Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Gross loans before unearned discounts and deferred fees, net	258,458		275,511
Allowance for loan losses	$ (3,479)	$ (4,008)	$ (4,370)	$ (4,341)	$ (4,370)	$ (3,563)