v2.4.0.6
Investments (Schedule of Contractual Maturities of Fixed Maturity Investments) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2013
Dec. 31, 2012
Trading Securities [Abstract]    
Amortized Cost, Due in less than one year $ 216,198  
Amortized Cost, Due after one through five years 2,613,378  
Amortized Cost, Due after five through ten years 549,292  
Amortized Cost, Due after ten years 129,104  
Trading Debt Securities, Amortized Cost Basis 4,430,285  
Trading Securities, Debt Maturities, within One Year, Fair Value 215,538  
Trading Securities, Debt Maturities, after One Through Five Years, Fair Value 2,636,410  
Trading Securities, Debt Maturities, after Five Through Ten Years, Fair Value 568,695  
Trading Securities, Debt Maturities, after Ten Years, Fair Value 141,455  
Trading Securities 4,511,885  
Available-for-sale Securities [Abstract]    
Available for Sale, Amortized Cost, Due in less than one year 0  
Available for Sale, Amortized Cost, Due after one through five years 2,312  
Available for Sale, Amortized Cost, Due after five through ten years 1,155  
Available for Sale, Amortized Cost, Due after ten years 786  
Available for Sale, Amortized Cost 39,324 71,445
Available for Sale, Fair Value, Due in less than one year 0  
Available for Sale, Fair Value, Due after one through five years 2,648  
Available for Sale, Fair Value, Due after five through ten years 1,234  
Available for Sale, Fair Value, Due after ten years 940  
Available for Sale, Fair Value 45,254 83,442
Fixed Maturity Investments [Abstract]    
Debt Securities, Amortized Cost, Due in less than one year 216,198  
Debt Securities, Amortized Cost, Due after one through five years 2,615,690  
Debt Securities, Amortized Cost, Due after five through ten years 550,447  
Debt Securities, Amortized Cost, Due after ten years 129,890  
Debt Securities, Amortized Cost 4,469,609  
Debt Securities, Fair Value, Due in less than one year 215,538  
Debt Securities, Fair Value, Due after one through give years 2,639,058  
Debt Securities, Fair Value, Due after five through ten years 569,929  
Debt Securities, Fair Value, Due after ten years 142,395  
Debt Securities, Fair Value 4,557,139  
Mortgage-backed [Member]
   
Trading Securities [Abstract]    
Trading Debt Securities, Amortized Cost Basis 914,832  
Trading Securities 941,878  
Available-for-sale Securities [Abstract]    
Available for Sale, Amortized Cost 30,998  
Available for Sale, Fair Value 35,978  
Fixed Maturity Investments [Abstract]    
Debt Securities, Amortized Cost 945,830  
Debt Securities, Fair Value 977,856  
Asset-backed [Member]
   
Trading Securities [Abstract]    
Trading Debt Securities, Amortized Cost Basis 7,481  
Trading Securities 7,909  
Available-for-sale Securities [Abstract]    
Available for Sale, Amortized Cost 4,073  
Available for Sale, Fair Value 4,454  
Fixed Maturity Investments [Abstract]    
Debt Securities, Amortized Cost 11,554  
Debt Securities, Fair Value $ 12,363