Investment Securities (Summary Of Net Gain From Sale Of Agency Securities) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011
Document Period End Date	Jun. 30, 2012
Proceeds from agency MBS sold				$ (2,545)		$ (3,050)
Net gains on sale of agency MBS	417			633		98
Agency Securities [Member]
Agency MBS sold, at cost	(25,843)			(35,086)		12,384
Proceeds from agency MBS sold	(26,260)	[1]		(35,719)	[1]	(12,482)
Gross gains on sale of agency MBS	425			645		109
Gross losses on sale of agency MBS	(8)			(12)		11
Net gains on sale of agency MBS	$ 417		$ 94	$ 633		$ 98

[1] Proceeds include cash received during the period, plus receivable for agency MBS sold during the period as of period end.