Securities - Fair Value and Age of Gross Unrealized Losses of Debt Securities (Details) $ in Thousands	Mar. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Number of Securities
Less Than 12 Months | security	25	15
12 Months or More | security	118	118
Total | security	143	133
Fair Value
Less Than 12 Months	$ 119,692	$ 45,297
12 Months or More	788,370	794,365
Total	908,062	839,662
Unrealized Losses
Less Than 12 Months	(1,063)	(371)
12 Months or More	(87,348)	(83,380)
Total	$ (88,411)	$ (83,751)
U.S. Treasury securities
Number of Securities
Less Than 12 Months | security	1	1
12 Months or More | security	13	13
Total | security	14	14
Fair Value
Less Than 12 Months	$ 9,956	$ 10,036
12 Months or More	122,630	123,750
Total	132,586	133,786
Unrealized Losses
Less Than 12 Months	(119)	(52)
12 Months or More	(11,304)	(10,454)
Total	$ (11,423)	$ (10,506)
Obligations of U.S. government corporations and agencies
Number of Securities
Less Than 12 Months | security	0	0
12 Months or More | security	5	5
Total | security	5	5
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or More	32,593	32,513
Total	32,593	32,513
Unrealized Losses
Less Than 12 Months	0	0
12 Months or More	(709)	(829)
Total	$ (709)	$ (829)
Collateralized mortgage obligations of U.S. government corporations and agencies
Number of Securities
Less Than 12 Months | security	8	4
12 Months or More | security	58	57
Total | security	66	61
Fair Value
Less Than 12 Months	$ 74,366	$ 35,161
12 Months or More	355,094	351,220
Total	429,460	386,381
Unrealized Losses
Less Than 12 Months	(741)	(318)
12 Months or More	(50,021)	(47,753)
Total	$ (50,762)	$ (48,071)
Residential mortgage-backed securities of U.S. government corporations and agencies
Number of Securities
Less Than 12 Months | security	11	10
12 Months or More | security	14	14
Total | security	25	24
Fair Value
Less Than 12 Months	$ 91	$ 100
12 Months or More	36,394	37,877
Total	36,485	37,977
Unrealized Losses
Less Than 12 Months	(1)	(1)
12 Months or More	(7,055)	(6,536)
Total	$ (7,056)	$ (6,537)
Commercial mortgage-backed securities of U.S. government corporations and agencies
Number of Securities
Less Than 12 Months | security	1	0
12 Months or More | security	28	29
Total | security	29	29
Fair Value
Less Than 12 Months	$ 10,274	$ 0
12 Months or More	241,659	249,005
Total	251,933	249,005
Unrealized Losses
Less Than 12 Months	(74)	0
12 Months or More	(18,259)	(17,808)
Total	$ (18,333)	$ (17,808)
Obligations of states and political subdivisions
Number of Securities
Less Than 12 Months | security	4
12 Months or More | security	0
Total | security	4
Fair Value
Less Than 12 Months	$ 25,005
12 Months or More	0
Total	25,005
Unrealized Losses
Less Than 12 Months	(128)
12 Months or More	0
Total	$ (128)