Securities - Gross Unrealized Losses and Fair Value by Investment Category (Details) $ in Thousands	Mar. 31, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Available for Sale:
Number of positions, Less than 12 Months | security	219	121
Fair Value, Less than 12 Months	$ 1,987,809	$ 1,899,384
Unrealized Losses, Less than 12 Months	$ (133,960)	$ (30,120)
Number of positions, 12 Months or More | security	22	7
Fair value, 12 Months or More	$ 173,753	$ 25,634
Unrealized Losses, 12 Months or More	$ (18,543)	$ (904)
Number of positions | security	241	128
Fair Value	$ 2,161,562	$ 1,925,018
Unrealized Losses	$ (152,503)	$ (31,024)
Held to Maturity:
Number of positions, Less than 12 Months | security	197	90
Fair Value, Less than 12 Months	$ 416,494	$ 201,791
Unrealized Losses, Less than 12 Months	$ (34,916)	$ (1,154)
Number of positions, 12 Months or More | security	4	1
Fair Value, 12 Months or More	$ 33,047	$ 5,354
Unrealized Losses, 12 Months or More	$ (2,769)	$ (17)
Number of positions | security	201	91
Fair Value	$ 449,541	$ 207,145
Unrealized Losses	$ (37,685)	$ (1,171)
Obligations of states and political subdivisions
Available for Sale:
Number of positions, Less than 12 Months | security	41	8
Fair Value, Less than 12 Months	$ 81,646	$ 34,303
Unrealized Losses, Less than 12 Months	$ (4,767)	$ (216)
Number of positions, 12 Months or More | security	4	3
Fair value, 12 Months or More	$ 5,805	$ 3,892
Unrealized Losses, 12 Months or More	$ (438)	$ (53)
Number of positions | security	45	11
Fair Value	$ 87,451	$ 38,195
Unrealized Losses	$ (5,205)	$ (269)
Held to Maturity:
Number of positions, Less than 12 Months | security	127	24
Fair Value, Less than 12 Months	$ 261,920	$ 62,131
Unrealized Losses, Less than 12 Months	$ (26,786)	$ (685)
Number of positions, 12 Months or More | security	1	0
Fair Value, 12 Months or More	$ 1,699	$ 0
Unrealized Losses, 12 Months or More	$ (183)	$ 0
Number of positions | security	128	24
Fair Value	$ 263,619	$ 62,131
Unrealized Losses	$ (26,969)	$ (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	10	1
Fair Value, Less than 12 Months	$ 51,369	$ 8,699
Unrealized Losses, Less than 12 Months	$ (1,991)	$ (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	10	1
Fair Value	$ 51,369	$ 8,699
Unrealized Losses	$ (1,991)	$ (148)
Held to Maturity:
Number of positions, Less than 12 Months | security	8	8
Fair Value, Less than 12 Months	$ 20,818	$ 21,972
Unrealized Losses, Less than 12 Months	$ (1,120)	$ (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	$ 20,818	$ 21,972
Unrealized Losses	$ (1,120)	$ (79)
Government agency mortgage backed securities | Residential mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	80	41
Fair Value, Less than 12 Months	$ 761,484	$ 727,546
Unrealized Losses, Less than 12 Months	$ (43,653)	$ (6,312)
Number of positions, 12 Months or More | security	6	1
Fair value, 12 Months or More	$ 49,651	$ 12,305
Unrealized Losses, 12 Months or More	$ (4,840)	$ (504)
Number of positions | security	86	42
Fair Value	$ 811,135	$ 739,851
Unrealized Losses	$ (48,493)	$ (6,816)
Held to Maturity:
Number of positions, Less than 12 Months | security	55	50
Fair Value, Less than 12 Months	$ 86,842	$ 53,560
Unrealized Losses, Less than 12 Months	$ (3,599)	$ (181)
Number of positions, 12 Months or More | security	1	1
Fair Value, 12 Months or More	$ 4,584	$ 5,354
Unrealized Losses, 12 Months or More	$ (344)	$ (17)
Number of positions | security	56	51
Fair Value	$ 91,426	$ 58,914
Unrealized Losses	$ (3,943)	$ (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	$ 10,481	$ 1,791
Unrealized Losses, Less than 12 Months	$ (371)	$ (1)
Number of positions, 12 Months or More | security	1	1
Fair value, 12 Months or More	$ 425	$ 432
Unrealized Losses, 12 Months or More	$ 0	$ 0
Number of positions | security	4	2
Fair Value	$ 10,906	$ 2,223
Unrealized Losses	$ (371)	$ (1)
Held to Maturity:
Number of positions, Less than 12 Months | security	1
Fair Value, Less than 12 Months	$ 15,534
Unrealized Losses, Less than 12 Months	$ (1,488)
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	$ 15,534
Unrealized Losses	$ (1,488)
Government agency collateralized mortgage obligations | Residential mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	61	49
Fair Value, Less than 12 Months	$ 932,820	$ 966,126
Unrealized Losses, Less than 12 Months	$ (74,437)	$ (20,371)
Number of positions, 12 Months or More | security	4	0
Fair value, 12 Months or More	$ 77,376	$ 0
Unrealized Losses, 12 Months or More	$ (9,154)	$ 0
Number of positions | security	65	49
Fair Value	$ 1,010,196	$ 966,126
Unrealized Losses	$ (83,591)	$ (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	$ 21,499	$ 0
Unrealized Losses, 12 Months or More	$ (1,904)	$ 0
Number of positions | security	1	1
Fair Value	$ 21,499	$ 24,740
Unrealized Losses	$ (1,904)	$ (92)
Government agency collateralized mortgage obligations | Commercial mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	24	21
Fair Value, Less than 12 Months	$ 150,009	$ 160,919
Unrealized Losses, Less than 12 Months	$ (8,741)	$ (3,072)
Number of positions, 12 Months or More | security	7	2
Fair value, 12 Months or More	$ 40,496	$ 9,005
Unrealized Losses, 12 Months or More	$ (4,111)	$ (347)
Number of positions | security	31	23
Fair Value	$ 190,505	$ 169,924
Unrealized Losses	$ (12,852)	$ (3,419)
Held to Maturity:
Number of positions, Less than 12 Months | security	6	7
Fair Value, Less than 12 Months	$ 31,380	$ 39,388
Unrealized Losses, Less than 12 Months	$ (1,923)	$ (117)
Number of positions, 12 Months or More | security	1	0
Fair Value, 12 Months or More	$ 5,265	$ 0
Unrealized Losses, 12 Months or More	$ (338)	$ 0
Number of positions | security	7	7
Fair Value	$ 36,645	$ 39,388
Unrealized Losses	$ (2,261)	$ (117)