Separate Accounts - Additional Information (Details) (USD $)
Sep. 30, 2014
Dec. 31, 2013
Sep. 30, 2014
Reinsurance transaction
Apr. 30, 2013
Reinsurance transaction
Sep. 30, 2014
Guaranteed minimum withdrawal benefit
Dec. 31, 2013
Guaranteed minimum withdrawal benefit
Net Amount at Risk by Product and Guarantee [Line Items]            
Value of variable annuity separate accounts         $ 131,700,000 $ 123,900,000
Separate accounts guarantee liability         (2,500,000) (4,700,000)
Modified Coinsurance Transaction Separate Account Fund Balances     317,800,000      
Fund value 2,082,347,000 2,096,212,000 26,300,000 23,600,000    
Future policy benefits $ 927,307,000 $ 910,228,000 $ 600,000 $ 600,000