Loans Receivable - Loan Portfolio by Portfolio Segment and by Class of Financing Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	$ 11,354,364		$ 11,414,809
Allowance for credit losses	125,070	$ 124,897	125,243	$ 124,423	$ 121,257	$ 118,036
Nonaccrual loans	102,159		94,384			81,236
Loans 90 days past due and accruing	2,511		2,698
Personal Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	6,584,612		6,782,070
Allowance for credit losses	43,241	44,668	51,706	50,851	51,617	48,887
Nonaccrual loans	15,067		18,264			15,746
Loans 90 days past due and accruing	2,002		2,463
Personal Banking | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	3,324,068		3,428,185
Allowance for credit losses	14,999	16,821	18,193	17,556	19,238	19,261
Nonaccrual loans	6,403		8,727			7,574
Loans 90 days past due and accruing	1,390		1,671
Personal Banking | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	1,180,486		1,227,858
Allowance for credit losses	5,210	5,334	5,403	5,002	5,481	5,902
Nonaccrual loans	4,055		4,492			4,145
Loans 90 days past due and accruing	34		26
Personal Banking | Vehicle loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	1,960,928		2,008,601
Allowance for credit losses	21,364	21,061	26,911	27,283	26,166	23,059
Nonaccrual loans	4,342		4,816			3,771
Loans 90 days past due and accruing	8		44
Personal Banking | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	119,130		117,426
Allowance for credit losses	1,668	1,452	1,199	1,010	732	665
Nonaccrual loans	267		229			256
Loans 90 days past due and accruing	570		722
Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	4,769,752		4,632,739
Allowance for credit losses	81,829	80,229	73,537	73,572	69,640	69,149
Nonaccrual loans	87,092		76,120			65,490
Loans 90 days past due and accruing	509		235
Commercial Banking | Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	2,665,016		2,628,457
Allowance for credit losses	50,559	54,474	51,267	50,056	45,404	44,506
Nonaccrual loans	73,989		71,297			62,239
Loans 90 days past due and accruing	185		225
Commercial Banking | Commercial real estate loans - owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	362,622		345,553
Allowance for credit losses	3,615	4,055	3,775	3,498	3,351	4,004
Nonaccrual loans	983		676			624
Loans 90 days past due and accruing	0		0
Commercial Banking | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	1,742,114		1,658,729
Allowance for credit losses	27,655	$ 21,700	18,495	$ 20,018	$ 20,885	20,639
Nonaccrual loans	12,120		4,147			$ 2,627
Loans 90 days past due and accruing	$ 324		$ 10