Investments and Derivative Instruments (Details 2) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Other-Than-Temporary Impairment Losses
Balance as of beginning of period	$ (2,003)	$ (2,341)	$ (2,072)	$ (2,200)
Additions for credit impairments recognized on securities not previously impaired	(8)	(52)	(36)	(164)
Additions for credit impairments recognized on securities previously impaired	(8)	(52)	(25)	(91)
Reductions for credit impairments previously recognized on Securities that matured or were sold during the period	83	151	192	154
Securities due to an increase in expected cash flows	3	13	8	20
Balance as of end of period	$ (1,933)	$ (2,281)	$ (1,933)	$ (2,281)