Debt Securities - Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Debt Securities
Number of Securities | security	662	713
Less than 12 Months, Fair Value	$ 57,410	$ 29,403
Less than 12 Months, Unrealized Loss	(1,351)	(370)
12 Months or More, Fair Value	4,165,269	4,679,701
12 Months or More, Unrealized Loss	(409,981)	(498,005)
Total, Fair Value	4,222,679	4,709,104
Total, Unrealized Loss	$ (411,332)	$ (498,375)
U.S. government and federal agency
Debt Securities
Number of Securities | security	55	57
Less than 12 Months, Fair Value	$ 3,756	$ 3,702
Less than 12 Months, Unrealized Loss	(34)	(56)
12 Months or More, Fair Value	463,151	448,909
12 Months or More, Unrealized Loss	(15,620)	(29,613)
Total, Fair Value	466,907	452,611
Total, Unrealized Loss	$ (15,654)	$ (29,669)
U.S. government sponsored enterprises
Debt Securities
Number of Securities | security	14	14
Less than 12 Months, Fair Value	$ 0	$ 0
Less than 12 Months, Unrealized Loss	0	0
12 Months or More, Fair Value	310,154	299,220
12 Months or More, Unrealized Loss	(13,700)	(22,774)
Total, Fair Value	310,154	299,220
Total, Unrealized Loss	$ (13,700)	$ (22,774)
State and local governments
Debt Securities
Number of Securities | security	50	85
Less than 12 Months, Fair Value	$ 3,653	$ 3,039
Less than 12 Months, Unrealized Loss	(35)	(2)
12 Months or More, Fair Value	49,748	64,645
12 Months or More, Unrealized Loss	(3,237)	(3,271)
Total, Fair Value	53,401	67,684
Total, Unrealized Loss	$ (3,272)	$ (3,273)
Corporate bonds
Debt Securities
Number of Securities | security	2	4
Less than 12 Months, Fair Value	$ 0	$ 0
Less than 12 Months, Unrealized Loss	0	0
12 Months or More, Fair Value	13,707	23,262
12 Months or More, Unrealized Loss	(315)	(756)
Total, Fair Value	13,707	23,262
Total, Unrealized Loss	$ (315)	$ (756)
Residential mortgage-backed securities
Debt Securities
Number of Securities | security	389	402
Less than 12 Months, Fair Value	$ 13,535	$ 1,430
Less than 12 Months, Unrealized Loss	(240)	(44)
12 Months or More, Fair Value	2,341,700	2,809,482
12 Months or More, Unrealized Loss	(304,579)	(355,289)
Total, Fair Value	2,355,235	2,810,912
Total, Unrealized Loss	$ (304,819)	$ (355,333)
Commercial mortgage-backed securities
Debt Securities
Number of Securities | security	152	151
Less than 12 Months, Fair Value	$ 36,466	$ 21,232
Less than 12 Months, Unrealized Loss	(1,042)	(268)
12 Months or More, Fair Value	986,809	1,034,183
12 Months or More, Unrealized Loss	(72,530)	(86,302)
Total, Fair Value	1,023,275	1,055,415
Total, Unrealized Loss	$ (73,572)	$ (86,570)