Investments - Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	$ 1,072,241	$ 1,218,279
Short term investments, Estimated Fair Value	5	0
Equity securities, Estimated Fair Value	234,697	264,945
Level 1 Inputs
Fair value of financial instruments
Marketable Securities, Total	189,731	224,677
Level 1 Inputs \| Equity securities
Fair value of financial instruments
Equity securities, Estimated Fair Value	189,731	224,677
Level 2 Inputs
Fair value of financial instruments
Marketable Securities, Total	1,072,246	1,218,279
Level 2 Inputs \| U.S. Treasury securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	1,721	324
Level 2 Inputs \| Obligations of states and political subdivisions
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	74,969	116,302
Level 2 Inputs \| Residential mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	223,380	241,464
Level 2 Inputs \| Commercial mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	147,737	150,883
Level 2 Inputs \| Other asset-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	70,528	83,596
Level 2 Inputs \| Corporate and other securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	553,906	625,710
Level 2 Inputs \| Short term Investments.
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	5
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	1,264,032	1,444,654
Estimated Fair Value \| U.S. Treasury securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	1,721	324
Estimated Fair Value \| Obligations of states and political subdivisions
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	74,969	116,302
Estimated Fair Value \| Residential mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	223,380	241,464
Estimated Fair Value \| Commercial mortgage-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	147,737	150,883
Estimated Fair Value \| Other asset-backed securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	70,528	83,596
Estimated Fair Value \| Corporate and other securities
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	553,906	625,710
Estimated Fair Value \| Short term Investments.
Fair value of financial instruments
Fixed maturity securities, Estimated Fair Value	5
Estimated Fair Value \| Equity securities
Fair value of financial instruments
Equity securities, Estimated Fair Value	$ 191,786	$ 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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