Investments - Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	$ 1,136,068	$ 1,218,279
Short term investments, Estimated Fair Value	5	0
Equity securities, Estimated Fair Value	258,699	264,945
Level 1 Inputs
Fair value of financial instruments
Marketable Securities, Total	216,331	224,677
Level 1 Inputs \| Equity securities
Fair value of financial instruments
Equity securities, Estimated Fair Value	216,331	224,677
Level 2 Inputs
Fair value of financial instruments
Marketable Securities, Total	1,136,073	1,218,279
Level 2 Inputs \| U.S. Treasury securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	1,756	324
Level 2 Inputs \| Obligations of states and political subdivisions
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	89,703	116,302
Level 2 Inputs \| Residential mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	221,187	241,464
Level 2 Inputs \| Commercial mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	149,824	150,883
Level 2 Inputs \| Other asset-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	72,819	83,596
Level 2 Inputs \| Corporate and other securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	600,779	625,710
Level 2 Inputs \| Short term Investments.
Fair value of financial instruments
Short term investments, Estimated Fair Value	5
Level 3 Inputs
Fair value of financial instruments
Marketable Securities, Total	1,698	1,698
Level 3 Inputs \| Equity securities
Fair value of financial instruments
Equity securities, Estimated Fair Value	1,698	1,698
Total
Fair value of financial instruments
Marketable Securities, Total	1,354,102	1,444,654
Total \| U.S. Treasury securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	1,756	324
Total \| Obligations of states and political subdivisions
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	89,703	116,302
Total \| Residential mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	221,187	241,464
Total \| Commercial mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	149,824	150,883
Total \| Other asset-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	72,819	83,596
Total \| Corporate and other securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	600,779	625,710
Total \| Short term Investments.
Fair value of financial instruments
Short term investments, Estimated Fair Value	5
Total \| Equity securities
Fair value of financial instruments
Equity securities, Estimated Fair Value	$ 218,029	$ 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).

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Amount of investment in marketable security.

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