Schedule I - Summary Of Investments Other -Than-Investments In Related Parties (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	$ 9,470,795	$ 10,048,100
Fixed maturity securities, fair value	10,215,328	$ 11,263,174
Cost or Amortized Cost	12,200,745
Fair Value	13,045,322
Amount at which shown in balance sheet	12,994,772
Fixed maturity securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	9,470,795
Fixed maturity securities, fair value	10,215,328
Amount at which shown in balance sheet	10,215,328
United States Government and government agencies and authorities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	150,681
Fixed maturity securities, fair value	154,035
Amount at which shown in balance sheet	154,035
State, municipalities and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	647,335
Fixed maturity securities, fair value	695,630
Amount at which shown in balance sheet	695,630
Foreign governments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	497,785
Fixed maturity securities, fair value	562,250
Amount at which shown in balance sheet	562,250
Asset-backed
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	3,499
Fixed maturity securities, fair value	4,662
Amount at which shown in balance sheet	4,662
Commercial mortgage-backed
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	22,169
Fixed maturity securities, fair value	22,521
Amount at which shown in balance sheet	22,521
Residential mortgage-backed
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	953,247
Fixed maturity securities, fair value	998,514
Amount at which shown in balance sheet	998,514
Corporate
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturity securities available for sale, amortized cost	7,196,079
Fixed maturity securities, fair value	7,777,716
Amount at which shown in balance sheet	7,777,716
Equity securities:
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	450,563
Fair Value	500,057
Amount at which shown in balance sheet	500,057
Common stocks
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	13,048
Fair Value	19,664
Amount at which shown in balance sheet	19,664
Non-redeemable preferred stocks
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	437,515
Fair Value	480,393
Amount at which shown in balance sheet	480,393
Commercial mortgage loans on real estate
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,151,256
Fair Value	1,201,806
Amount at which shown in balance sheet	1,151,256
Policy loans
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	43,858
Fair Value	43,858
Amount at which shown in balance sheet	43,858
Short-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	508,950
Fair Value	508,950
Amount at which shown in balance sheet	508,950
Other investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	575,323
Fair Value	575,323
Amount at which shown in balance sheet	$ 575,323