Loans - Consumer, Excluding Credit Card Loans, PCI Delinquency Statistics (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 779,705	$ 747,508	$ 735,369
Consumer, excluding credit card
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 316,781	294,979	$ 288,214
Consumer, excluding credit card | Purchased Credit-Impaired, Home Equity Senior Lien
Loans and Leases Receivable Disclosure [Line Items]
Percentage of senior liens to total financing receivables	20.00%
Consumer, excluding credit card | Purchased Credit-Impaired, Home Equity Junior Lien, Excluding Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 651	$ 736
Total 30 plus day delinquency rate	5.68%	8.83%
Consumer, excluding credit card | Purchased Credit-Impaired, Home Equity Junior Lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 12,796	$ 13,851
Total 30 plus day delinquency rate	4.72%	6.55%
Consumer, excluding credit card | HELOC, Within the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 7,004	$ 8,972
Total 30 plus day delinquency rate	4.35%	6.42%
Home equity line of credit, open-ended revolving period	10 years
Consumer, excluding credit card | HELOCs, Beyond the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 5,141	$ 4,143
Total 30 plus day delinquency rate	5.10%	6.42%