Investments - Security Holdings in an Unrealized Loss Position - Tabular Disclosure (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair Value
Fair Value - Less Than 12 Months	$ 408,309	$ 160,773
Fair Value - More Than 12 Months	29,367	9,346
Fair Value - Total	437,676	170,119
Unrealized Losses
Unrealized Losses - Less Than 12 Months	(30,685)	(2,188)
Unrealized Losses - More Than 12 Months	(4,267)	(517)
Unrealized Losses - Total	(34,952)	(2,705)
U.S. Governments
Fair Value
Fair Value - Less Than 12 Months	37,120	5,968
Fair Value - More Than 12 Months	6,478	1,457
Fair Value - Total	43,598	7,425
Unrealized Losses
Unrealized Losses - Less Than 12 Months	(659)	(147)
Unrealized Losses - More Than 12 Months	(573)	(43)
Unrealized Losses - Total	(1,232)	(190)
States, territories, and possessions
Fair Value
Fair Value - Less Than 12 Months	1,669	1,444
Fair Value - Total	1,669	1,444
Unrealized Losses
Unrealized Losses - Less Than 12 Months	(360)	(63)
Unrealized Losses - Total	(360)	(63)
Political subdivisions
Fair Value
Fair Value - Less Than 12 Months	4,015	1,815
Fair Value - More Than 12 Months	1,546
Fair Value - Total	5,561	1,815
Unrealized Losses
Unrealized Losses - Less Than 12 Months	(435)	(22)
Unrealized Losses - More Than 12 Months	(272)
Unrealized Losses - Total	(707)	(22)
Special revenue excluding mortgage/asset-backed securities
Fair Value
Fair Value - Less Than 12 Months	37,841	6,280
Fair Value - Total	37,841	6,280
Unrealized Losses
Unrealized Losses - Less Than 12 Months	(4,154)	(76)
Unrealized Losses - Total	(4,154)	(76)
Corporate and other
Fair Value
Fair Value - Less Than 12 Months	203,674	94,020
Fair Value - More Than 12 Months	15,103	5,570
Fair Value - Total	218,777	99,590
Unrealized Losses
Unrealized Losses - Less Than 12 Months	(16,868)	(1,468)
Unrealized Losses - More Than 12 Months	(2,742)	(423)
Unrealized Losses - Total	(19,610)	(1,891)
Mortgage/asset-backed securities
Fair Value
Fair Value - Less Than 12 Months	123,990	51,246
Fair Value - More Than 12 Months	6,240	2,319
Fair Value - Total	130,230	53,565
Unrealized Losses
Unrealized Losses - Less Than 12 Months	(8,209)	(412)
Unrealized Losses - More Than 12 Months	(680)	(51)
Unrealized Losses - Total	$ (8,889)	$ (463)

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