Schedule I Summary of Investments Other Than Investments in Related Parties (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Summary of Investments
Total investments, Cost	$ 6,306,996	[1]
Total investments, Fair Value	0
Total investments, Amount shown in Balance Sheet	6,539,473
Mortgage loans [Member]
Summary of Investments
Total investments, Cost	79	[1]
Total investments, Fair Value	0
Total investments, Amount shown in Balance Sheet	79
Short-term investments [Member]
Summary of Investments
Total investments, Cost	206,753	[1]
Total investments, Fair Value	0
Total investments, Amount shown in Balance Sheet	206,758
Policy loans [Member]
Summary of Investments
Total investments, Cost	140,607	[1]
Total investments, Fair Value	0
Total investments, Amount shown in Balance Sheet	140,607
Other [Member]
Summary of Investments
Total investments, Cost	90,598	[1]
Total investments, Fair Value	0
Total investments, Amount shown in Balance Sheet	90,598
Fixed maturities [Member]
Summary of Investments
Total investments, Cost	5,784,205	[1]
Total investments, Fair Value	6,009,573
Total investments, Amount shown in Balance Sheet	6,009,573
Fixed maturities [Member] | U.S. Government and federally sponsored agency obligations [Member]
Summary of Investments
Total investments, Cost	1,004,634	[1]
Total investments, Fair Value	1,005,299
Total investments, Amount shown in Balance Sheet	1,005,299
Fixed maturities [Member] | States, municipalities and political subdivisions [Member]
Summary of Investments
Total investments, Cost	1,425,441	[1]
Total investments, Fair Value	1,471,527
Total investments, Amount shown in Balance Sheet	1,471,527
Fixed maturities [Member] | Foreign government bonds [Member]
Summary of Investments
Total investments, Cost	50,641	[1]
Total investments, Fair Value	54,951
Total investments, Amount shown in Balance Sheet	54,951
Fixed maturities [Member] | Public utilities [Member]
Summary of Investments
Total investments, Cost	206,445	[1]
Total investments, Fair Value	234,540
Total investments, Amount shown in Balance Sheet	234,540
Fixed maturities [Member] | Other bonds [Member]
Summary of Investments
Total investments, Cost	3,097,044	[1]
Total investments, Fair Value	3,243,256
Total investments, Amount shown in Balance Sheet	3,243,256
Equity securities [Member]
Summary of Investments
Total investments, Cost	84,754	[1]
Total investments, Fair Value	91,858
Total investments, Amount shown in Balance Sheet	91,858
Equity securities [Member] | Non-redeemable preferred stocks [Member]
Summary of Investments
Total investments, Cost	22,172	[1]
Total investments, Fair Value	20,968
Total investments, Amount shown in Balance Sheet	20,968
Equity securities [Member] | Common stocks [Member]
Summary of Investments
Total investments, Cost	42,578	[1]
Total investments, Fair Value	52,961
Total investments, Amount shown in Balance Sheet	52,961
Equity securities [Member] | Closed End Fund [Member]
Summary of Investments
Total investments, Cost	20,004	[1]
Total investments, Fair Value	17,929
Total investments, Amount shown in Balance Sheet	$ 17,929

[1] Bonds at original cost reduced by repayments and adjusted for amortization of premiums or accrual of discounts and impairment in value of specifically identified investments.