Investments (Details 25) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components of Sales or Disposals of Fixed Maturity and Equity Securities
Proceeds	$ 60,867	$ 68,690	$ 55,130
Gross investment gains	1,017	1,000	960
Gross investment losses	(726)	(938)	(627)
Total OTTI losses recognized in earnings:
Credit-related	(223)	(645)	(423)
Other	(128)	(370)	(61)
Total OTTI losses recognized in earnings	(351)	(1,015)	(484)
Net investment gains (losses)	(60)	(953)	(151)
Fixed maturity securities [Member]
Components of Sales or Disposals of Fixed Maturity and Equity Securities
Proceeds	59,219	67,449	54,514
Gross investment gains	944	892	831
Gross investment losses	(691)	(867)	(616)
Total OTTI losses recognized in earnings:
Credit-related	(223)	(645)	(423)
Other	(94)	(310)	(47)
Total OTTI losses recognized in earnings	(317)	(955)	(470)
Net investment gains (losses)	(64)	(930)	(255)
Equity Securities [Member]
Components of Sales or Disposals of Fixed Maturity and Equity Securities
Proceeds	1,648	1,241	616
Gross investment gains	73	108	129
Gross investment losses	(35)	(71)	(11)
Total OTTI losses recognized in earnings:
Credit-related	0	0	0
Other	(34)	(60)	(14)
Total OTTI losses recognized in earnings	(34)	(60)	(14)
Net investment gains (losses)	$ 4	$ (23)	$ 104