Investments (Maturities of Fixed Maturity Securities) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, Due in one year or less	$ 20,433	$ 24,177
Amortized Cost, Due after one year through five years	69,684	66,973
Amortized Cost, Due after five years through ten years	77,693	82,376
Amortized Cost, Due after ten years	100,339	97,739
Amortized Cost, Subtotal	268,149	271,265
Amortized Cost, RMBS, CMBS and ABS	67,477	69,605
Amortized cost of fixed maturity securities available-for-sale	335,626	340,870
Estimated Fair Value, Due in one year or less	20,684	24,394
Estimated Fair Value, Due after one year through five years	73,065	70,759
Estimated Fair Value, Due after five years through ten years	84,144	91,975
Estimated Fair Value, Due after ten years	109,262	114,533
Estimated Fair Value, Subtotal	287,155	301,661
Estimated fair value, Mortgage-backed and asset-backed securities	69,359	72,605
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $335,626 and $340,870, respectively; includes $4,064 and $3,378, respectively, relating to variable interest entities)	$ 356,514	$ 374,266