Investments and Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Investments and Derivative Instruments [Abstract]
Document Period End Date			Sep. 30, 2012
Change in non-credit impairments of debt securities recognized in OCI
OTTI losses recognized in OCI	$ (22)	$ (11)	$ (37)	$ (83)
Changes in fair value and/or sales	91	21	125	88
Tax and deferred acquisition costs	(34)	0	(48)	6
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 35	$ 10	$ 40	$ 11