Investments - Schedule of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,154,867	$ 725,830
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	90,505	7,842
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	75,909	13,117
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	10,062	359
Debt Securities, Available-for-sale, Unrealized Loss Position	1,230,776	738,947
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	100,567	8,201
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	208,467	163,634
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	11,431	1,775
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	11,109	4,874
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	891	126
Debt Securities, Available-for-sale, Unrealized Loss Position	219,576	168,508
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	12,322	1,901
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	425,420	242,188
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	55,979	2,361
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	17,224	1,776
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,636	49
Debt Securities, Available-for-sale, Unrealized Loss Position	442,644	243,964
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	59,615	2,410
Agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	405,833	259,047
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	22,383	3,685
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	47,576	6,467
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,535	184
Debt Securities, Available-for-sale, Unrealized Loss Position	453,409	265,514
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	27,918	3,869
U.S. Treasury bills
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	105,513	60,961
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	596	21
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
Debt Securities, Available-for-sale, Unrealized Loss Position	105,513	60,961
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	596	$ 21
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	9,634
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	116
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Unrealized Loss Position	9,634
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 116

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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-Name Accounting Standards Codification
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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