Securities - Schedule of Debt Securities (Details) - USD ($)	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 4,201,439,000	$ 4,143,163,000
Unrealized Gains	18,816,000	29,609,000
Unrealized Losses	(359,991,000)	(347,203,000)
Allowance for Credit Losses	0	0	$ 0
Fair Value	3,860,264,000	3,825,569,000
Government-sponsored residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,830,011,000	2,753,311,000
Unrealized Gains	12,734,000	19,846,000
Unrealized Losses	(248,238,000)	(239,848,000)
Allowance for Credit Losses	0	0
Fair Value	2,594,507,000	2,533,309,000
Government-sponsored commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,132,808,000	1,148,394,000
Unrealized Gains	5,927,000	9,388,000
Unrealized Losses	(98,881,000)	(97,451,000)
Allowance for Credit Losses	0	0
Fair Value	1,039,854,000	1,060,331,000
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	50,020,000	50,030,000
Unrealized Gains	155,000	320,000
Unrealized Losses	0	0
Allowance for Credit Losses	0	0
Fair Value	50,175,000	50,350,000
State and municipal bonds and obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	188,600,000	191,428,000
Unrealized Gains	0	55,000
Unrealized Losses	(12,872,000)	(9,904,000)
Allowance for Credit Losses	0	0
Fair Value	$ 175,728,000	$ 181,579,000

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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