Schedule I - Summary of Investments - Other than Investments in Related Parties (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Summary of investments - other than investments in related parties
Cost or Amortized Cost	$ 1,380,756
Estimated Fair Value	1,442,955
Amount at which shown in the Balance Sheet	1,442,955
Total fixed maturities
Summary of investments - other than investments in related parties
Cost or Amortized Cost	1,192,357
Estimated Fair Value	1,228,040
Amount at which shown in the Balance Sheet	1,228,040
U.S. government and government agencies and authorities
Summary of investments - other than investments in related parties
Cost or Amortized Cost	303,007
Estimated Fair Value	308,714
Amount at which shown in the Balance Sheet	308,714
Obligations of states and political subdivisions
Summary of investments - other than investments in related parties
Cost or Amortized Cost	241,597
Estimated Fair Value	251,396
Amount at which shown in the Balance Sheet	251,396
Corporate and other securities
Summary of investments - other than investments in related parties
Cost or Amortized Cost	647,753
Estimated Fair Value	667,930
Amount at which shown in the Balance Sheet	667,930
Total equity securities
Summary of investments - other than investments in related parties
Cost or Amortized Cost	151,121
Estimated Fair Value	177,637
Amount at which shown in the Balance Sheet	177,637
Industrial, miscellaneous and all other
Summary of investments - other than investments in related parties
Cost or Amortized Cost	151,121
Estimated Fair Value	177,637
Amount at which shown in the Balance Sheet	177,637
Other invested assets
Summary of investments - other than investments in related parties
Cost or Amortized Cost	37,278
Estimated Fair Value	37,278
Amount at which shown in the Balance Sheet	$ 37,278