Investments (Maturities of Fixed Maturity Securities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, Due in one year or less	$ 23,879	$ 24,177
Amortized Cost, Due after one year through five years	70,432	66,973
Amortized Cost, Due after five years through ten years	80,420	82,376
Amortized Cost, Due after ten years	100,543	97,739
Amortized Cost, Subtotal	275,274	271,265
Amortized Cost, RMBS, CMBS and ABS	67,259	69,605
Amortized cost of fixed maturity securities available-for-sale	342,533	340,870
Estimated Fair Value, Due in one year or less	24,118	24,394
Estimated Fair Value, Due after one year through five years	74,386	70,759
Estimated Fair Value, Due after five years through ten years	89,648	91,975
Estimated Fair Value, Due after ten years	115,784	114,533
Estimated Fair Value, Subtotal	303,936	301,661
Estimated fair value, Mortgage-backed and asset-backed securities	70,358	72,605
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $342,533 and $340,870, respectively; includes $3,873 and $3,378, respectively, relating to variable interest entities)	$ 374,294	$ 374,266