Securities, AFS Securities in Continuous Unrealized Loss Position (Details) $ in Thousands	Mar. 31, 2022 USD ($) Position	Dec. 31, 2021 USD ($) Position
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 1,142,258	$ 811,115
12 months or longer	440,297	253,578
Total	1,582,555	1,064,693
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(56,606)	(13,238)
12 months or longer	(42,735)	(8,704)
Total	$ (99,341)	$ (21,942)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	270	127
12 months or longer | Position	51	22
Total | Position	321	149
AIR on AFS debt securities	$ 4,000	$ 3,900
U.S. Treasury [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	117,635	49,105
12 months or longer	0	0
Total	117,635	49,105
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(4,809)	(6)
12 months or longer	0	0
Total	$ (4,809)	$ (6)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	7	2
12 months or longer | Position	0	0
Total | Position	7	2
Federal Agency [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 2,586	$ 41,618
12 months or longer	223,026	198,313
Total	225,612	239,931
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(269)	(1,846)
12 months or longer	(22,564)	(6,677)
Total	$ (22,833)	$ (8,523)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	1	4
12 months or longer | Position	15	12
Total | Position	16	16
State & Municipal [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 74,201	$ 87,515
12 months or longer	14,097	0
Total	88,298	87,515
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(5,690)	(1,559)
12 months or longer	(1,347)	0
Total	$ (7,037)	$ (1,559)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	55	61
12 months or longer | Position	10	0
Total | Position	65	61
Mortgage-Backed [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 333,335	$ 281,217
12 months or longer	182,752	39,491
Total	516,087	320,708
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(11,186)	(4,319)
12 months or longer	(17,177)	(1,525)
Total	$ (28,363)	$ (5,844)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	105	24
12 months or longer | Position	19	6
Total | Position	124	30
Collateralized Mortgage Obligations [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 569,994	$ 341,673
12 months or longer	20,422	15,774
Total	590,416	357,447
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(33,158)	(5,495)
12 months or longer	(1,647)	(502)
Total	$ (34,805)	$ (5,997)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	88	34
12 months or longer | Position	7	4
Total | Position	95	38
Corporate [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 44,507	$ 9,987
12 months or longer	0	0
Total	44,507	9,987
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(1,494)	(13)
12 months or longer	0	0
Total	$ (1,494)	$ (13)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	14	2
12 months or longer | Position	0	0
Total | Position	14	2