Investment Securities - Schedule of Securities With Unrealized Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, less than 12 months, estimated fair value	$ 16,863	$ 37,952
Available-for-sale, less than 12 months, gross unrealized losses	(280)	(411)
Available-for-sale, 12 months or more, estimated fair value	2,291,619	2,429,271
Available-for-sale, 12 months or more, gross unrealized losses	(359,370)	(323,244)
Available-for-sale, total, estimated fair value	2,308,482	2,467,223
Available-for-sale, total, gross unrealized losses	(359,650)	(323,655)
U.S. Treasury
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, less than 12 months, estimated fair value	0	0
Available-for-sale, less than 12 months, gross unrealized losses	0	0
Available-for-sale, 12 months or more, estimated fair value	0	996
Available-for-sale, 12 months or more, gross unrealized losses	0	(3)
Available-for-sale, total, estimated fair value	0	996
Available-for-sale, total, gross unrealized losses	0	(3)
U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, less than 12 months, estimated fair value	1,286	717
Available-for-sale, less than 12 months, gross unrealized losses	(14)	(7)
Available-for-sale, 12 months or more, estimated fair value	45,388	51,186
Available-for-sale, 12 months or more, gross unrealized losses	(699)	(1,040)
Available-for-sale, total, estimated fair value	46,674	51,903
Available-for-sale, total, gross unrealized losses	(713)	(1,047)
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, less than 12 months, estimated fair value	0	7,480
Available-for-sale, less than 12 months, gross unrealized losses	0	(189)
Available-for-sale, 12 months or more, estimated fair value	1,331,598	1,384,532
Available-for-sale, 12 months or more, gross unrealized losses	(114,416)	(152,595)
Available-for-sale, total, estimated fair value	1,331,598	1,392,012
Available-for-sale, total, gross unrealized losses	(114,416)	(152,784)
State and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, less than 12 months, estimated fair value	7,757	16,843
Available-for-sale, less than 12 months, gross unrealized losses	(148)	(195)
Available-for-sale, 12 months or more, estimated fair value	778,668	829,754
Available-for-sale, 12 months or more, gross unrealized losses	(234,325)	(157,374)
Available-for-sale, total, estimated fair value	786,425	846,597
Available-for-sale, total, gross unrealized losses	(234,473)	(157,569)
Other securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, less than 12 months, estimated fair value	7,820	12,912
Available-for-sale, less than 12 months, gross unrealized losses	(118)	(20)
Available-for-sale, 12 months or more, estimated fair value	135,965	162,803
Available-for-sale, 12 months or more, gross unrealized losses	(9,930)	(12,232)
Available-for-sale, total, estimated fair value	143,785	175,715
Available-for-sale, total, gross unrealized losses	$ (10,048)	$ (12,252)