Investments (Maturities of Fixed Maturity Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, Due in one year or less	$ 13,401
Amortized Cost, Due after one year through five years	72,334
Amortized Cost, Due after five years through ten years	70,970
Amortized Cost, Due after ten years	107,644
Amortized Cost, RMBS, CMBS and ABS	64,854
Amortized Cost, Subtotal	329,203	$ 334,780
Estimated Fair Value, Due in one year or less	13,476
Estimated Fair Value, Due after one year through five years	75,724
Estimated Fair Value, Due after five years through ten years	74,741
Estimated Fair Value, Due after ten years	121,093
Estimated fair value, Mortgage-backed and asset-backed securities	66,544
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $329,203 and $334,780, respectively; includes $4,293 and $4,266, respectively, relating to variable interest entities)	$ 351,578	$ 365,425