Schedule I. Summary of Investments - Other than Investments in Related Parties (Details) $ in Thousands	Dec. 31, 2021 USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	$ 1,872,987
Fair Value	2,066,371
Amounts at Which Shown in Balance Sheet	2,064,686
Fixed Maturities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	1,656,797
Fair Value	1,719,790
Amounts at Which Shown in Balance Sheet	1,719,790
United States Government and government agencies and authorities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	102,499
Fair Value	103,590
Amounts at Which Shown in Balance Sheet	103,590
States, municipalities and political subdivisions
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	776,775
Fair Value	822,570
Amounts at Which Shown in Balance Sheet	822,570
Foreign governments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	30,314
Fair Value	30,906
Amounts at Which Shown in Balance Sheet	30,906
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	104,008
Fair Value	107,493
Amounts at Which Shown in Balance Sheet	107,493
All other bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	643,201
Fair Value	655,231
Amounts at Which Shown in Balance Sheet	655,231
Equity Securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	84,606
Fair Value	213,401
Amounts at Which Shown in Balance Sheet	213,401
Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	3,650
Fair Value	17,940
Amounts at Which Shown in Balance Sheet	17,940
Banks, trusts and insurance companies
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	12,626
Fair Value	45,823
Amounts at Which Shown in Balance Sheet	45,823
Industrial, miscellaneous and all other
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	67,735
Fair Value	149,043
Amounts at Which Shown in Balance Sheet	149,043
Nonredeemable preferred stocks
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	595
Fair Value	595
Amounts at Which Shown in Balance Sheet	595
Mortgage loans on real estate
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	47,201
Fair Value	48,815
Amounts at Which Shown in Balance Sheet	47,130
Other long-term investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	84,108
Fair Value	84,090
Amounts at Which Shown in Balance Sheet	84,090
Short-term investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost or Amortized Cost	275
Fair Value	275
Amounts at Which Shown in Balance Sheet	$ 275