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Loans Receivable - Originated and Acquired Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Jun. 30, 2026	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	$ 13,393,296		$ 13,007,316
Allowance for credit losses	(149,626)	$ (149,321)	(150,212)	$ (157,396)	$ (129,159)	$ (116,819)
Total loans receivable, net	13,243,670		12,857,104
Unearned income, unamortized premiums and discounts and deferred fees and costs	25,000		8,000
Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	7,398,846		7,172,202
Allowance for credit losses	(45,950)	(45,423)	(47,457)	(48,168)	(39,805)	(43,464)
Personal Banking \| Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,984,204		3,100,780
Allowance for credit losses	(10,309)	(10,174)	(10,546)	(11,592)	(12,089)	(14,347)
Personal Banking \| Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	1,496,559		1,507,532
Allowance for credit losses	(6,488)	(6,211)	(6,149)	(7,375)	(4,216)	(4,845)
Personal Banking \| Vehicle loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,779,278		2,426,636
Allowance for credit losses	(25,009)	(24,744)	(25,945)	(26,498)	(21,234)	(22,389)
Personal Banking \| Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	138,805		137,254
Allowance for credit losses	(4,144)	(4,294)	(4,817)	(2,703)	(2,266)	(1,883)
Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	5,994,450		5,835,114
Allowance for credit losses	(103,676)	(103,898)	(102,755)	(109,228)	(89,354)	(73,355)
Commercial Banking \| Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	2,559,351		2,915,696
Allowance for credit losses	(47,640)	(54,091)	(58,234)	(69,515)	(53,624)	(44,328)
Commercial Banking \| Commercial real estate loans - owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	372,250		381,206
Allowance for credit losses	(4,790)	(5,016)	(4,679)	(5,022)	(4,130)	(3,882)
Commercial Banking \| Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable, gross	3,062,849		2,538,212
Allowance for credit losses	$ (51,246)	$ (44,791)	$ (39,842)	$ (34,691)	$ (31,600)	$ (25,145)