Investment Securities Available-for-Sale - Gross unrealized losses and fair value (Details) $ in Thousands	Dec. 31, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	260	239
Less than 12 months, estimated fair value	$ 495,164	$ 1,891,310
Less than 12 months, unrealized losses	(58,439)	(24,285)
12 months or greater, estimated fair value	1,093,919	177,038
12 months or greater, unrealized losses	(146,839)	(5,322)
Estimated Fair Value	1,589,083	2,068,348
Unrealized Losses	$ (205,278)	$ (29,607)
Number of Securities | security	232
Less than 12 months, estimated fair value	$ 23,881
Less than 12 months, unrealized losses	3,228
12 months or greater, estimated fair value	932,753
12 months or greater, unrealized losses	122,205
Estimated Fair Value	956,634
Unrealized Losses	$ 125,433
Schedule of Held-to-Maturity Securities [Line Items]
Number of Securities | security	232
Less than 12 months, estimated fair value	$ 23,881
Less than 12 months, unrealized losses	3,228
12 months or greater, estimated fair value	932,753
12 months or greater, unrealized losses	122,205
Estimated Fair Value	956,634
Unrealized Losses	$ 125,433
U.S. treasury bonds
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	2	1
Less than 12 months, estimated fair value	$ 0	$ 24,593
Less than 12 months, unrealized losses	0	(257)
12 months or greater, estimated fair value	46,327	0
12 months or greater, unrealized losses	(3,466)	0
Estimated Fair Value	46,327	24,593
Unrealized Losses	$ (3,466)	$ (257)
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	85	64
Less than 12 months, estimated fair value	$ 490,699	$ 452,966
Less than 12 months, unrealized losses	(58,437)	(6,256)
12 months or greater, estimated fair value	179,029	68,977
12 months or greater, unrealized losses	(19,612)	(1,366)
Estimated Fair Value	669,728	521,943
Unrealized Losses	$ (78,049)	$ (7,622)
Residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	157	149
Less than 12 months, estimated fair value	$ 3,994	$ 1,327,519
Less than 12 months, unrealized losses	0	(16,841)
12 months or greater, estimated fair value	808,697	84,500
12 months or greater, unrealized losses	(117,073)	(3,606)
Estimated Fair Value	812,691	1,412,019
Unrealized Losses	$ (117,073)	$ (20,447)
Number of Securities | security	143
Less than 12 months, estimated fair value	$ 0
Less than 12 months, unrealized losses	0
12 months or greater, estimated fair value	652,667
12 months or greater, unrealized losses	88,390
Estimated Fair Value	652,667
Unrealized Losses	$ 88,390
Schedule of Held-to-Maturity Securities [Line Items]
Number of Securities | security	143
Less than 12 months, estimated fair value	$ 0
Less than 12 months, unrealized losses	0
12 months or greater, estimated fair value	652,667
12 months or greater, unrealized losses	88,390
Estimated Fair Value	652,667
Unrealized Losses	$ 88,390
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	14
Less than 12 months, estimated fair value	$ 471
Less than 12 months, unrealized losses	(2)
12 months or greater, estimated fair value	49,742
12 months or greater, unrealized losses	(5,855)
Estimated Fair Value	50,213
Unrealized Losses	$ (5,857)
Number of Securities | security	16	4
Less than 12 months, estimated fair value	$ 0	$ 0
Less than 12 months, unrealized losses	0	0
12 months or greater, estimated fair value	80,564	23,561
12 months or greater, unrealized losses	11,993	350
Estimated Fair Value	80,564	23,561
Unrealized Losses	$ 11,993	$ 350
Schedule of Held-to-Maturity Securities [Line Items]
Number of Securities | security	16	4
Less than 12 months, estimated fair value	$ 0	$ 0
Less than 12 months, unrealized losses	0	0
12 months or greater, estimated fair value	80,564	23,561
12 months or greater, unrealized losses	11,993	350
Estimated Fair Value	80,564	23,561
Unrealized Losses	$ 11,993	$ 350
US states and political subdivisions debt securities
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	1	8
Less than 12 months, estimated fair value	$ 0	$ 20,181
Less than 12 months, unrealized losses	0	(347)
12 months or greater, estimated fair value	8,299	0
12 months or greater, unrealized losses	(658)	0
Estimated Fair Value	8,299	20,181
Unrealized Losses	$ (658)	$ (347)
Number of Securities | security	43
Less than 12 months, estimated fair value	$ 3,110
Less than 12 months, unrealized losses	45
12 months or greater, estimated fair value	113,071
12 months or greater, unrealized losses	12,047
Estimated Fair Value	116,181
Unrealized Losses	$ 12,092
Schedule of Held-to-Maturity Securities [Line Items]
Number of Securities | security	43
Less than 12 months, estimated fair value	$ 3,110
Less than 12 months, unrealized losses	45
12 months or greater, estimated fair value	113,071
12 months or greater, unrealized losses	12,047
Estimated Fair Value	116,181
Unrealized Losses	$ 12,092
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	1	13
Less than 12 months, estimated fair value	$ 0	$ 66,051
Less than 12 months, unrealized losses	0	(584)
12 months or greater, estimated fair value	1,825	0
12 months or greater, unrealized losses	(175)	0
Estimated Fair Value	1,825	66,051
Unrealized Losses	$ (175)	$ (584)
Number of Securities | security	30
Less than 12 months, estimated fair value	$ 20,771
Less than 12 months, unrealized losses	3,183
12 months or greater, estimated fair value	86,451
12 months or greater, unrealized losses	9,775
Estimated Fair Value	107,222
Unrealized Losses	$ 12,958
Schedule of Held-to-Maturity Securities [Line Items]
Number of Securities | security	30
Less than 12 months, estimated fair value	$ 20,771
Less than 12 months, unrealized losses	3,183
12 months or greater, estimated fair value	86,451
12 months or greater, unrealized losses	9,775
Estimated Fair Value	107,222
Unrealized Losses	$ 12,958