Investments - Schedule of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 47,210	$ 127,160
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	281	714
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,269,984	1,326,392
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	127,328	151,750
Debt Securities, Available-for-sale, Unrealized Loss Position	1,317,194	1,453,552
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	127,609	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	999	25,886
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	85
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	250,613	247,027
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	12,495	20,283
Debt Securities, Available-for-sale, Unrealized Loss Position	251,612	272,913
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	12,496	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	3,338	1,168
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	100	163
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	418,471	428,171
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	69,497	68,604
Debt Securities, Available-for-sale, Unrealized Loss Position	421,809	429,339
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	69,597	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	42,873	58,249
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	180	417
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	509,144	540,032
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	43,527	58,666
Debt Securities, Available-for-sale, Unrealized Loss Position	552,017	598,281
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	43,707	59,083
U.S. Treasury bills
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	8,130	7,574
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	620	1,176
Debt Securities, Available-for-sale, Unrealized Loss Position	8,130	7,574
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	620	1,176
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	41,857
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	49
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	83,626	103,588
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,189	3,021
Debt Securities, Available-for-sale, Unrealized Loss Position	83,626	145,445
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 1,189	$ 3,070