Investment Securities (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Summary of other-than-temporary impairment by investment category
Other Gains (losses)		$ (5)
Available for sale Securities [Member]
Summary of other-than-temporary impairment by investment category
Other Gains (losses)		(5)
Losses Recorded in Earnings	(9)	(6)
Total Available for sale other-than-temporary impairment	(9)	(11)
Available for sale Securities [Member] | Other asset-backed securities [Member]
Summary of other-than-temporary impairment by investment category
Other Gains (losses)	1
Losses Recorded in Earnings	(1)
Available for sale Securities [Member] | Non-agency [Member] | Residential [Member]
Summary of other-than-temporary impairment by investment category
Other Gains (losses)	(1)
Losses Recorded in Earnings
Total Available for sale other-than-temporary impairment	(1)
Available for sale Securities [Member] | Residential Non-agency Prime [Member] | Residential [Member]
Summary of other-than-temporary impairment by investment category
Other Gains (losses)	(3)	1
Losses Recorded in Earnings	(1)	(1)
Total Available for sale other-than-temporary impairment	(4)
Available for sale Securities [Member] | Residential Non-agency Non-Prime [Member] | Residential [Member]
Summary of other-than-temporary impairment by investment category
Other Gains (losses)	3	(6)
Losses Recorded in Earnings	(7)	(5)
Total Available for sale other-than-temporary impairment	$ (4)	$ (11)