Investments In Fixed Maturity Securities Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 856,512
Amortized Cost, Due after one year through five years	3,648,617
Amortized Cost, Due after five years through ten years	3,121,394
Amortized Cost, Due after ten years	2,580,536
Amortized Cost, Mortgaged-backed securities	1,362,000
Total investments in fixed maturity securities, Amortized Value	11,569,059	11,291,631
Fair Value, Due in one year or less	870,324
Fair Value, Due after one year through five years	3,797,781
Fair Value, Due after five years through ten years	3,292,088
Fair Value, Due after ten years	2,665,594
Fair Value, Mortgage-backed securities	1,378,528
Total investments in fixed maturity securities, Fair Value	$ 12,004,315	$ 11,631,744