Asset Quality (Details 11) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Changes in the liability for credit losses on lending-related commitments
Beginning Balance	$ 73	$ 121	$ 54
Provision (credit) for losses on lending-related commitments	(28)	(48)	67
Ending Balance	$ 45	$ 73	$ 121