Securities (Schedule of Credit Losses on Other-than-Temporarily Impaired Non-agency Mortgage-Backed Securities where Portion of the Unrealized Loss was Recognized in Other Comprehensive Income) (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Securities
Balance at beginning of period	$ 51	$ 8	$ 30	$ 2
Credit losses on securities not previously considered other-than-temporarily impaired		1		2
Credit losses on securities for which OTTI was previously recognized	18	4	39	9
Reductions for securities sold/settled during the period	(6)		(6)
Balance at end of period	$ 63	$ 13	$ 63	$ 13