Investments in Securities Other-than-temporary Impairments 3 (Details) (Available-for-sale Securities [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Available-for-sale Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance, beginning of period	$ 9,366	$ 7,876	$ 8,915	$ 8,215
Additions for the credit component on debt securities for which OTTI was not previously recognized	11	0	13	8
Additions for the credit component on debt securities for which OTTI was previously recognized	27	262	688	354
Reductions for securities no longer in portfolio at period end	(1)	(5)	(3)	(5)
Reductions for amortizations resulting from changes in cash flows expected to be collected over the remaining life of the securities	(91)	(253)	(301)	(692)
Balance, end of period	$ 9,312	$ 7,880	$ 9,312	$ 7,880