Securities - Gross Unrealized Losses and Fair Value by Investment Category (Details) $ in Thousands	Jun. 30, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Available for Sale:
Number of positions, Less than 12 Months | security	295	121
Fair Value, Less than 12 Months	$ 2,096,955	$ 1,899,384
Unrealized Losses, Less than 12 Months	$ (185,483)	$ (30,120)
Number of positions, 12 Months or More | security	33	7
Fair value, 12 Months or More	$ 292,496	$ 25,634
Unrealized Losses, 12 Months or More	$ (41,704)	$ (904)
Number of positions | security	328	128
Fair Value	$ 2,389,451	$ 1,925,018
Unrealized Losses	$ (227,187)	$ (31,024)
Held to Maturity:
Number of positions, Less than 12 Months | security	196	90
Fair Value, Less than 12 Months	$ 384,047	$ 201,791
Unrealized Losses, Less than 12 Months	$ (59,122)	$ (1,154)
Number of positions, 12 Months or More | security	6	1
Fair Value, 12 Months or More	$ 31,876	$ 5,354
Unrealized Losses, 12 Months or More	$ (5,188)	$ (17)
Number of positions | security	202	91
Fair Value	$ 415,923	$ 207,145
Unrealized Losses	$ (64,310)	$ (1,171)
Obligations of other U.S. Government agencies and corporations
Available for Sale:
Number of positions, Less than 12 Months | security	3
Fair Value, Less than 12 Months	$ 119,357
Unrealized Losses, Less than 12 Months	$ (643)
Number of positions, 12 Months or More | security	0
Fair value, 12 Months or More	$ 0
Unrealized Losses, 12 Months or More	$ 0
Number of positions | security	3
Fair Value	$ 119,357
Unrealized Losses	$ (643)
Obligations of states and political subdivisions
Available for Sale:
Number of positions, Less than 12 Months | security	60	8
Fair Value, Less than 12 Months	$ 98,281	$ 34,303
Unrealized Losses, Less than 12 Months	$ (8,807)	$ (216)
Number of positions, 12 Months or More | security	4	3
Fair value, 12 Months or More	$ 5,615	$ 3,892
Unrealized Losses, 12 Months or More	$ (583)	$ (53)
Number of positions | security	64	11
Fair Value	$ 103,896	$ 38,195
Unrealized Losses	$ (9,390)	$ (269)
Held to Maturity:
Number of positions, Less than 12 Months | security	127	24
Fair Value, Less than 12 Months	$ 241,365	$ 62,131
Unrealized Losses, Less than 12 Months	$ (46,316)	$ (685)
Number of positions, 12 Months or More | security	1	0
Fair Value, 12 Months or More	$ 1,482	$ 0
Unrealized Losses, 12 Months or More	$ (401)	$ 0
Number of positions | security	128	24
Fair Value	$ 242,847	$ 62,131
Unrealized Losses	$ (46,717)	$ (685)
Trust preferred securities
Available for Sale:
Number of positions, Less than 12 Months | security		0
Fair Value, Less than 12 Months		$ 0
Unrealized Losses, Less than 12 Months		$ 0
Number of positions, 12 Months or More | security		0
Fair value, 12 Months or More		$ 0
Unrealized Losses, 12 Months or More		$ 0
Number of positions | security		0
Fair Value		$ 0
Unrealized Losses		$ 0
Other debt securities
Available for Sale:
Number of positions, Less than 12 Months | security	23	1
Fair Value, Less than 12 Months	$ 114,580	$ 8,699
Unrealized Losses, Less than 12 Months	$ (4,198)	$ (148)
Number of positions, 12 Months or More | security	0	0
Fair value, 12 Months or More	$ 0	$ 0
Unrealized Losses, 12 Months or More	$ 0	$ 0
Number of positions | security	23	1
Fair Value	$ 114,580	$ 8,699
Unrealized Losses	$ (4,198)	$ (148)
Held to Maturity:
Number of positions, Less than 12 Months | security	8	8
Fair Value, Less than 12 Months	$ 18,399	$ 21,972
Unrealized Losses, Less than 12 Months	$ (1,589)	$ (79)
Number of positions, 12 Months or More | security	0	0
Fair Value, 12 Months or More	$ 0	$ 0
Unrealized Losses, 12 Months or More	$ 0	$ 0
Number of positions | security	8	8
Fair Value	$ 18,399	$ 21,972
Unrealized Losses	$ (1,589)	$ (79)
Government agency mortgage backed securities | Residential mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	121	41
Fair Value, Less than 12 Months	$ 798,188	$ 727,546
Unrealized Losses, Less than 12 Months	$ (64,728)	$ (6,312)
Number of positions, 12 Months or More | security	10	1
Fair value, 12 Months or More	$ 79,131	$ 12,305
Unrealized Losses, 12 Months or More	$ (9,509)	$ (504)
Number of positions | security	131	42
Fair Value	$ 877,319	$ 739,851
Unrealized Losses	$ (74,237)	$ (6,816)
Held to Maturity:
Number of positions, Less than 12 Months | security	53	50
Fair Value, Less than 12 Months	$ 77,033	$ 53,560
Unrealized Losses, Less than 12 Months	$ (5,634)	$ (181)
Number of positions, 12 Months or More | security	3	1
Fair Value, 12 Months or More	$ 6,365	$ 5,354
Unrealized Losses, 12 Months or More	$ (910)	$ (17)
Number of positions | security	56	51
Fair Value	$ 83,398	$ 58,914
Unrealized Losses	$ (6,544)	$ (198)
Government agency mortgage backed securities | Commercial mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	3	1
Fair Value, Less than 12 Months	$ 10,255	$ 1,791
Unrealized Losses, Less than 12 Months	$ (568)	$ (1)
Number of positions, 12 Months or More | security	0	1
Fair value, 12 Months or More	$ 0	$ 432
Unrealized Losses, 12 Months or More	$ 0	$ 0
Number of positions | security	3	2
Fair Value	$ 10,255	$ 2,223
Unrealized Losses	$ (568)	$ (1)
Held to Maturity:
Number of positions, Less than 12 Months | security	1
Fair Value, Less than 12 Months	$ 14,741
Unrealized Losses, Less than 12 Months	$ (2,276)
Number of positions, 12 Months or More | security	0
Fair Value, 12 Months or More	$ 0
Unrealized Losses, 12 Months or More	$ 0
Number of positions | security	1
Fair Value	$ 14,741
Unrealized Losses	$ (2,276)
Government agency collateralized mortgage obligations | Residential mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	56	49
Fair Value, Less than 12 Months	$ 811,824	$ 966,126
Unrealized Losses, Less than 12 Months	$ (94,500)	$ (20,371)
Number of positions, 12 Months or More | security	11	0
Fair value, 12 Months or More	$ 167,946	$ 0
Unrealized Losses, 12 Months or More	$ (25,429)	$ 0
Number of positions | security	67	49
Fair Value	$ 979,770	$ 966,126
Unrealized Losses	$ (119,929)	$ (20,371)
Held to Maturity:
Number of positions, Less than 12 Months | security	0	1
Fair Value, Less than 12 Months	$ 0	$ 24,740
Unrealized Losses, Less than 12 Months	$ 0	$ (92)
Number of positions, 12 Months or More | security	1	0
Fair Value, 12 Months or More	$ 18,985	$ 0
Unrealized Losses, 12 Months or More	$ (3,375)	$ 0
Number of positions | security	1	1
Fair Value	$ 18,985	$ 24,740
Unrealized Losses	$ (3,375)	$ (92)
Government agency collateralized mortgage obligations | Commercial mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	29	21
Fair Value, Less than 12 Months	$ 144,470	$ 160,919
Unrealized Losses, Less than 12 Months	$ (12,039)	$ (3,072)
Number of positions, 12 Months or More | security	8	2
Fair value, 12 Months or More	$ 39,804	$ 9,005
Unrealized Losses, 12 Months or More	$ (6,183)	$ (347)
Number of positions | security	37	23
Fair Value	$ 184,274	$ 169,924
Unrealized Losses	$ (18,222)	$ (3,419)
Held to Maturity:
Number of positions, Less than 12 Months | security	7	7
Fair Value, Less than 12 Months	$ 32,509	$ 39,388
Unrealized Losses, Less than 12 Months	$ (3,307)	$ (117)
Number of positions, 12 Months or More | security	1	0
Fair Value, 12 Months or More	$ 5,044	$ 0
Unrealized Losses, 12 Months or More	$ (502)	$ 0
Number of positions | security	8	7
Fair Value	$ 37,553	$ 39,388
Unrealized Losses	$ (3,809)	$ (117)