Investments and Derivative Instruments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Sep. 30, 2011	Mar. 31, 2011
Investments and Derivative Instruments [Abstract]
Document Period End Date	Mar. 31, 2013
Other-Than-Temporary Impairment Losses
Balance as of beginning of period					$ (1,233)	$ (1,319)
Additions for credit impairments recognized on securities not previously impaired	(5)	[1]	(13)	[1]
Additions for credit impairments recognized on securities previously impaired	0	[1]	(3)	[1]
Securities that matured or were sold during the period	111		101
Securities due to an increase in expected cash flows	1		1
Balance as of end of period	$ 706		$ 813		$ (1,233)	$ (1,319)

[1] These additions are included in the net OTTI losses recognized in earnings in the Condensed Consolidated Statements of Operations.