Securities- Unrealized Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 3,171,284	$ 1,800,502
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	209,660	20,878
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	292,135	317,275
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	39,998	11,808
Total investments with an unrealized loss, fair value	3,463,419	2,117,777
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	249,658	32,686
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	182,142	178,610
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	685	881
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Total investments with an unrealized loss, fair value	182,142	178,610
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	685	881
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	386,971	353,951
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	22,017	2,987
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	28,543	54,266
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,616	1,974
Total investments with an unrealized loss, fair value	415,514	408,217
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	24,633	4,961
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,149,133	744,996
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	94,808	11,663
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	220,024	178,956
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	32,369	6,647
Total investments with an unrealized loss, fair value	1,369,157	923,952
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	127,177	18,310
State and municipal securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,238,230	309,605
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	76,205	2,198
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	19,632	57,270
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,136	1,045
Total investments with an unrealized loss, fair value	1,257,862	366,875
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	78,341	3,243
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	149,344	198,349
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	12,045	2,595
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	4,066	6,513
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	370	190
Total investments with an unrealized loss, fair value	153,410	204,862
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	12,415	2,785
Corporate notes
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	65,464	14,991
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3,900	554
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	19,870	20,270
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,507	1,952
Total investments with an unrealized loss, fair value	85,334	35,261
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	$ 6,407	$ 2,506