Investments - Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	$ 1,039,102	$ 1,218,279
Equity securities, Estimated Fair Value	225,967	264,945
Level 1 Inputs
Fair value of financial instruments
Marketable Securities, Total	181,611	224,677
Level 1 Inputs \| Equity securities
Fair value of financial instruments
Equity securities, Estimated Fair Value	181,611	224,677
Level 2 Inputs
Fair value of financial instruments
Marketable Securities, Total	1,039,102	1,218,279
Level 2 Inputs \| U.S. Treasury securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	1,657	324
Level 2 Inputs \| Obligations of states and political subdivisions
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	66,762	116,302
Level 2 Inputs \| Residential mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	220,735	241,464
Level 2 Inputs \| Commercial mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	136,738	150,883
Level 2 Inputs \| Other asset-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	69,475	83,596
Level 2 Inputs \| Corporate and other securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	543,735	625,710
Level 3 Inputs
Fair value of financial instruments
Marketable Securities, Total	2,055	1,698
Level 3 Inputs \| Equity securities
Fair value of financial instruments
Equity securities, Estimated Fair Value	2,055	1,698
Estimated Fair Value
Fair value of financial instruments
Marketable Securities, Total	1,222,768	1,444,654
Estimated Fair Value \| U.S. Treasury securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	1,657	324
Estimated Fair Value \| Obligations of states and political subdivisions
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	66,762	116,302
Estimated Fair Value \| Residential mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	220,735	241,464
Estimated Fair Value \| Commercial mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	136,738	150,883
Estimated Fair Value \| Other asset-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	69,475	83,596
Estimated Fair Value \| Corporate and other securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	543,735	625,710
Estimated Fair Value \| Equity securities
Fair value of financial instruments
Equity securities, Estimated Fair Value	$ 183,666	$ 226,375

Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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Amount of investment in marketable security.

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