Schedule I. Summary of Investments - Other than Investments in Related Parties (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	$ 1,630,224
Fair Value	1,888,933
Amounts at Which Shown in Balance Sheet	1,888,933
Fixed Maturities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,531,342
Fair Value	1,552,062
Amounts at Which Shown in Balance Sheet	1,552,062
United States Government and government agencies and authorities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	94,941
Fair Value	95,353
Amounts at Which Shown in Balance Sheet	95,353
States, municipalities and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,019,420
Fair Value	1,034,827
Amounts at Which Shown in Balance Sheet	1,034,827
Foreign governments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	10,865
Fair Value	11,130
Amounts at Which Shown in Balance Sheet	11,130
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	43,064
Fair Value	43,692
Amounts at Which Shown in Balance Sheet	43,692
All other bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	360,657
Fair Value	364,501
Amounts at Which Shown in Balance Sheet	364,501
Redeemable preferred stock
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2,395
Fair Value	2,559
Amounts at Which Shown in Balance Sheet	2,559
Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	63,275
Fair Value	287,344
Amounts at Which Shown in Balance Sheet	287,344
Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	4,661
Fair Value	16,060
Amounts at Which Shown in Balance Sheet	16,060
Banks, trusts and insurance companies
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	11,266
Fair Value	113,487
Amounts at Which Shown in Balance Sheet	113,487
Industrial, miscellaneous and all other
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	44,077
Fair Value	153,959
Amounts at Which Shown in Balance Sheet	153,959
Nonredeemable preferred stocks
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	3,271
Fair Value	3,838
Amounts at Which Shown in Balance Sheet	3,838
Other long-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	35,432
Fair Value	49,352
Amounts at Which Shown in Balance Sheet	49,352
Short-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	175
Fair Value	175
Amounts at Which Shown in Balance Sheet	175
Discontinued Operations
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,440,751
Fair Value	1,479,558
Amounts at Which Shown in Balance Sheet	1,479,399
Discontinued Operations | Fixed Maturities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,412,325
Fair Value	1,430,059
Amounts at Which Shown in Balance Sheet	1,430,059
Discontinued Operations | United States Government and government agencies and authorities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	43,706
Fair Value	43,706
Amounts at Which Shown in Balance Sheet	43,706
Discontinued Operations | States, municipalities and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	37,963
Fair Value	38,363
Amounts at Which Shown in Balance Sheet	38,363
Discontinued Operations | Foreign governments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	40,496
Fair Value	41,623
Amounts at Which Shown in Balance Sheet	41,623
Discontinued Operations | Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	162,964
Fair Value	165,452
Amounts at Which Shown in Balance Sheet	165,452
Discontinued Operations | All other bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,127,196
Fair Value	1,140,915
Amounts at Which Shown in Balance Sheet	1,140,915
Discontinued Operations | Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	5,099
Fair Value	23,653
Amounts at Which Shown in Balance Sheet	23,653
Discontinued Operations | Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2,544
Fair Value	7,253
Amounts at Which Shown in Balance Sheet	7,253
Discontinued Operations | Banks, trusts and insurance companies
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	467
Fair Value	3,158
Amounts at Which Shown in Balance Sheet	3,158
Discontinued Operations | Industrial, miscellaneous and all other
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2,088
Fair Value	13,242
Amounts at Which Shown in Balance Sheet	13,242
Discontinued Operations | Mortgage loans on real estate
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	3,435
Fair Value	3,594
Amounts at Which Shown in Balance Sheet	3,435
Discontinued Operations | Policy loans
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	5,815
Fair Value	5,815
Amounts at Which Shown in Balance Sheet	5,815
Discontinued Operations | Other long-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	14,077
Fair Value	16,437
Amounts at Which Shown in Balance Sheet	$ 16,437