Investments (Amortized Cost and Fair Value of Fixed Maturities by Contractual Maturities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Available For Sale Securities Debt Maturities Amortized Cost
Due in one year or less	$ 593,119
Due after one year through five years	4,100,619
Due after five year through ten years	7,604,908
Due after ten years	6,792,183
Asset and mortgage-backed securities	3,362,112
Total	22,452,941	20,270,734
Available For Sale Securities Debt Maturities Fair Value
Due in one year or less	599,642
Due after one year through five years	4,325,143
Due after five year through ten years	7,972,837
Due after ten years	8,089,242
Asset and mortgage-backed securities	3,488,587
Total	$ 24,475,451	$ 21,474,136