Investments and Derivative Instruments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Jun. 30, 2012	Jun. 30, 2011
Investments and Derivative Instruments [Abstract]
Document Period End Date	Mar. 31, 2013
Other-Than-Temporary Impairment Losses
Balance as of beginning of period					$ (1,013)	$ (1,676)
Additions for credit impairments recognized on securities not previously impaired	(8)	[1]	(12)	[1]
Additions for credit impairments recognized on securities previously impaired	(2)	[1]	(5)	[1]
Securities that matured or were sold during the period	114		160
Securities due to an increase in expected cash flows	3		3
Balance as of end of period	$ (906)		$ (1,530)		$ (1,013)	$ (1,676)

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