Investments (Maturities of Fixed Maturity Securities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, Due in one year or less	$ 13,740
Amortized Cost, Due after one year through five years	71,252
Amortized Cost, Due after five years through ten years	75,395
Amortized Cost, Due after ten years	104,239
Amortized Cost, RMBS, CMBS and ABS	68,283
Amortized Cost, Subtotal	332,909	334,780
Estimated Fair Value, Due in one year or less	13,916
Estimated Fair Value, Due after one year through five years	74,840
Estimated Fair Value, Due after five years through ten years	81,857
Estimated Fair Value, Due after ten years	124,759
Estimated fair value, Mortgage-backed and asset-backed securities	70,903
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $332,909 and $334,780, respectively; includes $4,326 and $4,266, respectively, relating to variable interest entities)	$ 366,275	$ 365,425