Loans and Allowance for Credit Losses - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2026 USD ($) loan	Mar. 31, 2025 USD ($) loan	Dec. 31, 2025 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 17,932,883,000		$ 17,492,179,000
Loan premiums and discounts	2,400,000		3,300,000
Deferred origination costs and fees	6,500,000		5,400,000
Financing receivable, accrued interest excluded from amortized costs	80,700,000		80,300,000
Nonaccrual loans with no allowance for credit loss	38,600,000		18,000,000.0
Financing receivable, collateral dependent, amount	110,365,000		112,374,000
Provision for credit loss expense	14,622,000	$ 26,797,000
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	$ 0
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in process of foreclosure, amount	$ 4,100,000		4,400,000
Commercial Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans experiencing financial difficulty, modified, subsequent default | loan	0	1
Loan modified and subsequently defaulted		$ 26,700,000
OREO Received in Full or Partial Satisfaction of Loans | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Foreclosed assets and other real estate owned	$ 3,900,000		$ 3,600,000
Loans, Excluding Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit loss expense	$ 14,622,000	26,797,000
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
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