Securities, Securities in Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Securities [Abstract]
Percentage of total investment with unrealized losses	98.70%	97.40%
Available-for-sale, amortized cost [Abstract]
Less than 12 months	$ 93,214	$ 416,778
12 months or more	1,254,300	981,280
Total	1,347,514	1,398,058
Available-for-sale, gross unrealized losses [Abstract]
Less than 12 months	(3,309)	(21,324)
12 months or more	(158,332)	(153,300)
Total	(161,641)	(174,624)
Available-for-sale, fair value [Abstract]
Less than 12 months	89,905	395,454
12 months or more	1,095,968	827,980
Total	1,185,873	1,223,434
U.S. Treasury and Government Agencies [Member]
Available-for-sale, amortized cost [Abstract]
Less than 12 months	7,188	144,305
12 months or more	380,143	249,424
Total	387,331	393,729
Available-for-sale, gross unrealized losses [Abstract]
Less than 12 months	(10)	(6,953)
12 months or more	(34,887)	(29,906)
Total	(34,897)	(36,859)
Available-for-sale, fair value [Abstract]
Less than 12 months	7,178	137,352
12 months or more	345,256	219,518
Total	352,434	356,870
State and Political Subdivisions [Member]
Available-for-sale, amortized cost [Abstract]
Less than 12 months	34,386	94,277
12 months or more	277,291	225,019
Total	311,677	319,296
Available-for-sale, gross unrealized losses [Abstract]
Less than 12 months	(1,493)	(6,257)
12 months or more	(52,732)	(55,419)
Total	(54,225)	(61,676)
Available-for-sale, fair value [Abstract]
Less than 12 months	32,893	88,020
12 months or more	224,559	169,600
Total	257,452	257,620
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Available-for-sale, amortized cost [Abstract]
Less than 12 months	51,640	139,314
12 months or more	507,278	454,357
Total	558,918	593,671
Available-for-sale, gross unrealized losses [Abstract]
Less than 12 months	(1,806)	(6,883)
12 months or more	(69,260)	(66,950)
Total	(71,066)	(73,833)
Available-for-sale, fair value [Abstract]
Less than 12 months	49,834	132,431
12 months or more	438,018	387,407
Total	487,852	519,838
Asset-backed Securities [Member]
Available-for-sale, amortized cost [Abstract]
Less than 12 months	0	38,882
12 months or more	89,588	52,480
Total	89,588	91,362
Available-for-sale, gross unrealized losses [Abstract]
Less than 12 months	0	(1,231)
12 months or more	(1,453)	(1,025)
Total	(1,453)	(2,256)
Available-for-sale, fair value [Abstract]
Less than 12 months	0	37,651
12 months or more	88,135	51,455
Total	$ 88,135	$ 89,106