Investments - Schedule of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 208,286	$ 127,160
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,423	714
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,320,313	1,326,392
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	164,751	151,750
Debt Securities, Available-for-sale, Unrealized Loss Position	1,528,599	1,453,552
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	166,174	152,464
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	22,611	25,886
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	72	85
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	251,397	247,027
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	20,910	20,283
Debt Securities, Available-for-sale, Unrealized Loss Position	274,008	272,913
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	20,982	20,368
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	479	1,168
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	163
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	420,164	428,171
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	77,266	68,604
Debt Securities, Available-for-sale, Unrealized Loss Position	420,643	429,339
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	77,268	68,767
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	125,634	58,249
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,240	417
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	531,490	540,032
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	62,470	58,666
Debt Securities, Available-for-sale, Unrealized Loss Position	657,124	598,281
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	63,710	59,083
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	7,811	7,574
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	939	1,176
Debt Securities, Available-for-sale, Unrealized Loss Position	7,811	7,574
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	939	1,176
U.S. Treasury bills
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	59,562	41,857
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	109	49
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	109,451	103,588
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,166	3,021
Debt Securities, Available-for-sale, Unrealized Loss Position	169,013	145,445
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 3,275	$ 3,070