Loans - Consumer, Excluding Credit Card Loans, Delinquency Statistics Junior Lien Home Equity Loans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Loans and Leases Receivable Disclosure [Line Items]
Total loans	$ 832,792	$ 747,508	$ 724,177
Consumer, excluding credit card
Loans and Leases Receivable Disclosure [Line Items]
Total loans	344,355	294,979	$ 288,449
Consumer, excluding credit card | HELOCs | Within the revolving period
Loans and Leases Receivable Disclosure [Line Items]
Total loans	$ 17,050	$ 25,252
Total 30 day delinquency rate	1.57%	1.75%
Open-ended revolving period	10 years
Amortization period	20 years
Consumer, excluding credit card | HELOCs | Beyond the revolving period
Loans and Leases Receivable Disclosure [Line Items]
Total loans	$ 11,252	$ 7,979
Total 30 day delinquency rate	3.10%	3.16%
Consumer, excluding credit card | HELOANs
Loans and Leases Receivable Disclosure [Line Items]
Total loans	$ 2,409	$ 3,144
Total 30 day delinquency rate	3.03%	3.34%
Consumer, excluding credit card | Junior lien | Home equity
Loans and Leases Receivable Disclosure [Line Items]
Total loans	$ 30,711	$ 36,375
Total 30 day delinquency rate	2.25%	2.20%