Receivables Held for Sale Receivables Held For Sale - Allowance for Credit Losses Rollforward (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 898	$ 1,452
Initial valuation allowance for receivables transferred to held for sale during the period	99	99
Release of valuation allowance resulting from improvements in fair value	(471)	(925)
Release of valuation allowance for collections, loans sold, charged-off, transferred to REO or short sale	(217)	(317)
Balance at end of period	$ 309	$ 309