Investment Securities (Other-Than-Temporary Impairment Recorded On Securities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other-than-temporary impairment recorded on securities	$ 73
2006 And 2007 Vintage US Residential Mortgage Backed Securities [Member]
Other-than-temporary impairment recorded on securities	12	158	109	[1]
2006 And 2007 Vintage US Residential Mortgage Backed Securities [Member] | Sub-Prime [Member]
Other-than-temporary impairment recorded on securities	2	26	29	[1]
2006 And 2007 Vintage US Residential Mortgage Backed Securities [Member] | Alt-A [Member]
Other-than-temporary impairment recorded on securities	5	43	20	[1]
2006 And 2007 Vintage US Residential Mortgage Backed Securities [Member] | Non-Agency Prime [Member]
Other-than-temporary impairment recorded on securities	$ 5	$ 89	$ 60	[1]

[1] Represents the period from April 1, 2009 through December 31, 2009, subsequent to the adoption of the revised GAAP related to other-than-temporary impairment.