Investments - Schedule of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 323,104	$ 722,676
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	7,828	45,806
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,195,337	756,002
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	172,224	147,922
Debt Securities, Available-for-sale, Unrealized Loss Position	1,518,441	1,478,678
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	180,052	193,728
Obligations of U.S. Government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	48,444	73,738
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,048	6,249
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	221,131	163,047
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	26,272	22,056
Debt Securities, Available-for-sale, Unrealized Loss Position	269,575	236,785
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	27,320	28,305
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	2,324	103,179
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	191	13,501
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	417,374	311,634
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	79,651	76,924
Debt Securities, Available-for-sale, Unrealized Loss Position	419,698	414,813
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	79,842	90,425
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	151,797	334,431
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5,165	20,038
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	473,248	281,321
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	61,842	48,942
Debt Securities, Available-for-sale, Unrealized Loss Position	625,045	615,752
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	67,007	68,980
U.S. Treasury bills
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,807	12,640
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	193	1,110
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	5,665	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,085	0
Debt Securities, Available-for-sale, Unrealized Loss Position	7,472	12,640
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1,278	1,110
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	118,732	198,688
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,231	4,908
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	77,919	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,374	0
Debt Securities, Available-for-sale, Unrealized Loss Position	196,651	198,688
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 4,605	$ 4,908