Loans - Net Gains and Losses on Sale (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Gains Losses On Loan Sales By Portfolio Segment [Line Items]
Gain (Loss) on Sales of Loans, Net	$ 293	$ 228	$ 464
Consumer, Excluding Credit Card
Net Gains Losses On Loan Sales By Portfolio Segment [Line Items]
Gain (Loss) on Sales of Loans, Net	122	131	265
Credit Card
Net Gains Losses On Loan Sales By Portfolio Segment [Line Items]
Gain (Loss) on Sales of Loans, Net	(9)	(24)	(16)
Wholesale
Net Gains Losses On Loan Sales By Portfolio Segment [Line Items]
Gain (Loss) on Sales of Loans, Net	$ 180	$ 121	$ 215