Loans - Consumer, Excluding Credit Card Loan Portfolio, PCI Delinquency Statistics (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 844,195	$ 832,792	$ 756,971
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	43,932	45,559
Consumer, excluding credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	353,871	344,355	$ 304,917
Consumer, excluding credit card | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 43,932	$ 45,559
Total 30 day delinquency rate	2.66%	2.77%
Consumer, excluding credit card | Home equity | Junior lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 29,388	$ 30,711
Total 30 day delinquency rate	2.10%	2.25%
Consumer, excluding credit card | Residential real estate – PCI | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 14,522	$ 14,989
Consumer, excluding credit card | Residential real estate – PCI | Home equity | Senior lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of senior liens to total financing receivables	23.00%
Consumer, excluding credit card | Residential real estate – PCI | Home equity | Junior lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 11,429	$ 11,834
Total 30 day delinquency rate	3.91%	4.35%
Consumer, excluding credit card | Residential real estate – PCI | HELOCs | Junior lien | Within the revolving period
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,277	$ 5,000
Total 30 day delinquency rate	3.62%	4.10%
Open-ended revolving period	10 years
Consumer, excluding credit card | Residential real estate – PCI | HELOCs | Junior lien | Beyond the revolving period
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 6,598	$ 6,252
Total 30 day delinquency rate	4.02%	4.46%
Consumer, excluding credit card | Residential real estate – PCI | HELOANs | Junior lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 554	$ 582
Total 30 day delinquency rate	4.87%	5.33%