Securities - Amortized Cost and Fair Value of Securities Available for Sale (Details) - USD ($)	Jun. 30, 2026	Dec. 31, 2025
Investments, Debt and Equity Securities [Abstract]
Allowance for credit loss	$ 0	$ 0
Amortized cost and fair value of securities available for sale
Amortized Cost	2,942,166,000	2,635,495,000
Gross Unrealized Gains	13,556,000	21,882,000
Gross Unrealized Losses	(113,298,000)	(96,559,000)
Fair Value	2,842,424,000	2,560,818,000
Obligations of states and political subdivisions
Amortized cost and fair value of securities available for sale
Amortized Cost	274,280,000	266,553,000
Gross Unrealized Gains	7,684,000	8,012,000
Gross Unrealized Losses	(3,740,000)	(1,780,000)
Fair Value	278,224,000	272,785,000
Other debt securities
Amortized cost and fair value of securities available for sale
Amortized Cost	346,458,000	349,132,000
Gross Unrealized Gains	845,000	1,537,000
Gross Unrealized Losses	(2,012,000)	(2,314,000)
Fair Value	345,291,000	348,355,000
Agency mortgage-backed securities \| Residential mortgage-backed securities:
Amortized cost and fair value of securities available for sale
Amortized Cost	1,051,549,000	793,154,000
Gross Unrealized Gains	758,000	5,670,000
Gross Unrealized Losses	(22,092,000)	(15,675,000)
Fair Value	1,030,215,000	783,149,000
Agency mortgage-backed securities \| Commercial mortgage-backed securities:
Amortized cost and fair value of securities available for sale
Amortized Cost	99,275,000	100,314,000
Gross Unrealized Gains	112,000	285,000
Gross Unrealized Losses	(818,000)	(762,000)
Fair Value	98,569,000	99,837,000
Collateralized mortgage obligations \| Residential mortgage-backed securities:
Amortized cost and fair value of securities available for sale
Amortized Cost	762,249,000	706,986,000
Gross Unrealized Gains	1,427,000	2,826,000
Gross Unrealized Losses	(64,315,000)	(57,908,000)
Fair Value	699,361,000	651,904,000
Collateralized mortgage obligations \| Commercial mortgage-backed securities:
Amortized cost and fair value of securities available for sale
Amortized Cost	408,355,000	419,356,000
Gross Unrealized Gains	2,730,000	3,552,000
Gross Unrealized Losses	(20,321,000)	(18,120,000)
Fair Value	$ 390,764,000	$ 404,788,000

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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Amount, before tax, of unrealized loss 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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Amount of allowance for credit loss 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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