Investment Securities - Amortized Cost and Fair Value by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Amortized Cost
Due in One Year or Less	$ 69,791
Due after One Year through Five Years	735,730
Due after Five Years through Ten Years	1,136,872
Due after Ten Years	962,352
Amortized Cost	2,904,745	$ 4,278,589
Fair Value
Due in One Year or Less	69,174
Due after One Year through Five Years	696,697
Due after Five Years through Ten Years	995,311
Due after Ten Years	839,831
Total	2,601,013	4,273,864
Amortized Cost
Due in One Year or Less	0
Due after One Year through Five Years	10,537
Due after Five Years through Ten Years	50,674
Due after Ten Years	1,326,935
Amortized Cost	1,388,146	381,696
Fair Value
Due in One Year or Less	0
Due after One Year through Five Years	9,893
Due after Five Years through Ten Years	43,861
Due after Ten Years	1,043,342
Total	1,097,096	384,423
Amortized Cost
Due in One Year or Less	69,791
Due after One Year through Five Years	746,267
Due after Five Years through Ten Years	1,187,546
Due after Ten Years	2,289,287
Total	4,292,891
Fair Value
Due in One Year or Less	69,174
Due after One Year through Five Years	706,590
Due after Five Years through Ten Years	1,039,172
Due after Ten Years	1,883,173
Estimated Fair Value	3,698,109
Treasury
Amortized Cost
Due in One Year or Less	9,743
Due after One Year through Five Years	24,475
Due after Five Years through Ten Years	14,938
Due after Ten Years	0
Amortized Cost	49,156	57,708
Fair Value
Due in One Year or Less	9,701
Due after One Year through Five Years	24,280
Due after Five Years through Ten Years	13,036
Due after Ten Years	0
Total	47,017	57,866
Agency
Amortized Cost
Due in One Year or Less	25,575
Due after One Year through Five Years	326,466
Due after Five Years through Ten Years	96,148
Due after Ten Years	37,142
Amortized Cost	485,331	440,183
Fair Value
Due in One Year or Less	25,281
Due after One Year through Five Years	299,758
Due after Five Years through Ten Years	78,702
Due after Ten Years	27,697
Total	431,438	432,135
Corporate
Amortized Cost
Due in One Year or Less	0
Due after One Year through Five Years	283,332
Due after Five Years through Ten Years	303,320
Due after Ten Years	0
Amortized Cost	586,652	451,621
Fair Value
Due in One Year or Less	0
Due after One Year through Five Years	273,415
Due after Five Years through Ten Years	269,133
Due after Ten Years	0
Total	542,548	453,861
Collateralized mortgage obligations
Amortized Cost
Due in One Year or Less	34,473
Due after One Year through Five Years	66,535
Due after Five Years through Ten Years	202,571
Due after Ten Years	526,349
Amortized Cost	829,928	680,686
Fair Value
Due in One Year or Less	34,192
Due after One Year through Five Years	64,986
Due after Five Years through Ten Years	180,391
Due after Ten Years	484,660
Total	764,229	676,643
Municipal bonds
Amortized Cost
Amortized Cost		1,061,985
Fair Value
Total		1,089,913
Amortized Cost
Due in One Year or Less	0
Due after One Year through Five Years	10,537
Due after Five Years through Ten Years	50,674
Due after Ten Years	1,086,844
Amortized Cost	1,148,055	368,344
Fair Value
Due in One Year or Less	0
Due after One Year through Five Years	9,893
Due after Five Years through Ten Years	43,861
Due after Ten Years	836,872
Total	890,626	370,507
Mortgage-backed securities
Amortized Cost
Due in One Year or Less	0
Due after One Year through Five Years	34,922
Due after Five Years through Ten Years	519,895
Due after Ten Years	398,861
Amortized Cost	953,678	1,586,406
Fair Value
Due in One Year or Less	0
Due after One Year through Five Years	34,258
Due after Five Years through Ten Years	454,049
Due after Ten Years	327,474
Total	815,781	1,563,446
Amortized Cost
Due in One Year or Less	0
Due after One Year through Five Years	0
Due after Five Years through Ten Years	0
Due after Ten Years	231,692
Amortized Cost	231,692	11,843
Fair Value
Due in One Year or Less	0
Due after One Year through Five Years	0
Due after Five Years through Ten Years	0
Due after Ten Years	198,071
Total	198,071	$ 12,407
Other
Amortized Cost
Due in One Year or Less	0
Due after One Year through Five Years	0
Due after Five Years through Ten Years	0
Due after Ten Years	8,399
Amortized Cost	8,399
Fair Value
Due in One Year or Less	0
Due after One Year through Five Years	0
Due after Five Years through Ten Years	0
Due after Ten Years	8,399
Total	$ 8,399