Loans and Allowance for Credit Losses - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2025 USD ($) loan	Mar. 31, 2024 USD ($) loan	Dec. 31, 2024 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 17,094,078,000		$ 17,005,937,000
Loan premiums and discounts	6,100,000		7,200,000
Deferred origination costs and fees	8,400,000		9,600,000
Financing receivable, accrued interest excluded from amortized costs	78,700,000		78,800,000
Nonaccrual loans with no allowance for credit loss	$ 1,100,000		1,700,000
Number of loan modifications | loan	0
Financing receivable, collateral dependent, amount	$ 95,399,000		102,580,000
Provision for credit loss expense	26,797,000	$ 10,206,000
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded commitments, allowance for credit loss	25,600,000		25,600,000
Reserve for unfunded commitments, expensed (released)	$ 0
Commercial Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans experiencing financial difficulty, modified, subsequent default | loan	1	1
Loan modified and subsequently defaulted	$ 26,900,000	$ 23,000
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit loss expense	26,797,000	$ 10,206,000
Loans, Excluding Acquired Loans | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit loss expense	$ 15,600,000
Number of credit relationships migrated to nonperforming | loan	2
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in process of foreclosure, amount	$ 5,900,000		4,000,000
Residential Real Estate | OREO Received in Full or Partial Satisfaction of Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Foreclosed assets and other real estate owned	1,200,000		1,300,000
Paycheck Protection Program Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,000,000.0		$ 1,600,000
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, term of loan	1 year
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, term of loan	3 years