Exit from Taxpayer Financial Services Loan Program (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Effects on Future Earnings and Cash flows Resulting from Exit Plan [Line Items]
Total revenues	$ 1,922	$ 2,266	$ 2,180
Income before income tax expense	(910)	682	1,445
Taxpayer Financial Services Loan Program [Member]
Schedule of Effects on Future Earnings and Cash flows Resulting from Exit Plan [Line Items]
Total revenues	0	0	69
Income before income tax expense	$ 0	$ 0	$ 11