Loans Loans - Purchased, Sold and Reclassified to Held-for-Sale (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Retained Loans Purchases Sales And Transfer Into Held For Sale By Portfolio Segment [Line Items]
Financing Receivable, Significant Purchases	$ 2,109	$ 2,107	$ 4,829	$ 4,187
Financing Receivable, Significant Sales	2,658	1,794	5,240	3,014
Financing Receivable, Reclassification to Held-for-Sale	1,385	175	1,729	1,160
Consumer, excluding credit card
Retained Loans Purchases Sales And Transfer Into Held For Sale By Portfolio Segment [Line Items]
Financing Receivable, Significant Purchases	1,590	1,854	4,215	3,613
Financing Receivable, Significant Sales	1,233	985	2,662	1,342
Financing Receivable, Reclassification to Held-for-Sale	708	0	708	0
Credit card
Retained Loans Purchases Sales And Transfer Into Held For Sale By Portfolio Segment [Line Items]
Financing Receivable, Significant Purchases	328	0	328	0
Financing Receivable, Significant Sales	0	0	0	0
Financing Receivable, Reclassification to Held-for-Sale	0	120	0	1,043
Wholesale
Retained Loans Purchases Sales And Transfer Into Held For Sale By Portfolio Segment [Line Items]
Financing Receivable, Significant Purchases	191	253	286	574
Financing Receivable, Significant Sales	1,425	809	2,578	1,672
Financing Receivable, Reclassification to Held-for-Sale	$ 677	$ 55	$ 1,021	$ 117