Investment Securities - Age of Unrealized Losses and Fair Value of Related Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Fair Value
Less than 12 Months	$ 621,685	$ 61,548
More than 12 Months	2,187,523	2,377,489
Total	2,809,208	2,439,037
Unrealized Losses
Less than 12 Months	(12,925)	(2,119)
More than 12 Months	(382,547)	(376,465)
Total	(395,472)	(378,584)
U.S. government agency securities
Fair Value
Less than 12 Months	0	0
More than 12 Months	232,530	235,027
Total	232,530	235,027
Unrealized Losses
Less than 12 Months	0	0
More than 12 Months	(42,066)	(39,226)
Total	(42,066)	(39,226)
Obligations of states and state agencies
Fair Value
Less than 12 Months	9,178	8,974
More than 12 Months	30,021	32,537
Total	39,199	41,511
Unrealized Losses
Less than 12 Months	(133)	(161)
More than 12 Months	(3,305)	(3,132)
Total	(3,438)	(3,293)
Municipal bonds
Fair Value
Less than 12 Months	55,956	18,237
More than 12 Months	143,223	176,687
Total	199,179	194,924
Unrealized Losses
Less than 12 Months	(5,944)	(1,777)
More than 12 Months	(13,998)	(15,518)
Total	(19,942)	(17,295)
Obligations of states and political subdivisions
Fair Value
Less than 12 Months	65,134	27,211
More than 12 Months	173,244	209,224
Total	238,378	236,435
Unrealized Losses
Less than 12 Months	(6,077)	(1,938)
More than 12 Months	(17,303)	(18,650)
Total	(23,380)	(20,588)
Residential mortgage-backed securities
Fair Value
Less than 12 Months	556,551	23,866
More than 12 Months	1,721,951	1,837,989
Total	2,278,502	1,861,855
Unrealized Losses
Less than 12 Months	(6,848)	(152)
More than 12 Months	(317,549)	(311,663)
Total	(324,397)	(311,815)
Trust preferred securities
Fair Value
Less than 12 Months	0	0
More than 12 Months	31,721	30,689
Total	31,721	30,689
Unrealized Losses
Less than 12 Months	0	0
More than 12 Months	(4,395)	(5,414)
Total	(4,395)	(5,414)
Corporate and other debt securities
Fair Value
Less than 12 Months	0	10,471
More than 12 Months	28,077	64,560
Total	28,077	75,031
Unrealized Losses
Less than 12 Months	0	(29)
More than 12 Months	(1,234)	(1,512)
Total	$ (1,234)	$ (1,541)

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

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