Investments (Maturities of Fixed Maturity Securities) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, Due in one year or less	$ 12,889
Amortized Cost, Due after one year through five years	71,122
Amortized Cost, Due after five years through ten years	72,803
Amortized Cost, Due after ten years	106,462
Amortized Cost, RMBS, CMBS and ABS	65,557
Amortized Cost, Subtotal	328,833	$ 334,780
Estimated Fair Value, Due in one year or less	13,015
Estimated Fair Value, Due after one year through five years	74,685
Estimated Fair Value, Due after five years through ten years	77,611
Estimated Fair Value, Due after ten years	118,692
Estimated fair value, Mortgage-backed and asset-backed securities	67,350
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $328,833 and $334,780, respectively; includes $4,335 and $4,266, respectively, relating to variable interest entities)	$ 351,353	$ 365,425