Investment Securities - Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Debt Securities Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,804,160	$ 3,552,273
Gross Unrealized Gains	16,574	4,063
Gross Unrealized Losses	(162,030)	(186,612)
Fair Value	3,658,704	3,369,724
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	321,009	319,551
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(24,756)	(28,002)
Fair Value	296,253	291,549
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	23,850	24,636
Gross Unrealized Gains	22	20
Gross Unrealized Losses	(1,472)	(2,113)
Fair Value	22,400	22,543
Obligations of states and state agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	45,848	46,211
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(840)	(682)
Fair Value	45,008	45,529
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	179,928	179,284
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(37,555)	(32,304)
Fair Value	142,373	146,980
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	225,776	225,495
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(38,395)	(32,986)
Fair Value	187,381	192,509
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,034,723	2,784,895
Gross Unrealized Gains	16,242	3,796
Gross Unrealized Losses	(83,430)	(107,615)
Fair Value	2,967,535	2,681,076
Corporate and other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	198,802	197,696
Gross Unrealized Gains	310	247
Gross Unrealized Losses	(13,977)	(15,896)
Fair Value	$ 185,135	$ 182,047