Loans - Consumer, Excluding Credit Card Loan Portfolio (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 889,907	$ 832,792	$ 747,508
Consumer, excluding credit card
Loans and Leases Receivable Disclosure [Line Items]
Retained	364,406	344,355	$ 294,979
Consumer, excluding credit card | Home equity
Loans and Leases Receivable Disclosure [Line Items]
Retained	39,063	45,559
Consumer, excluding credit card | Home equity | Residential real estate - PCI
Loans and Leases Receivable Disclosure [Line Items]
Retained	12,902	14,989
Consumer, excluding credit card | Residential mortgage
Loans and Leases Receivable Disclosure [Line Items]
Retained	192,163	166,239
Consumer, excluding credit card | Residential mortgage | Residential real estate - PCI
Loans and Leases Receivable Disclosure [Line Items]
Retained	35,679	40,998
Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Retained	65,814	60,255
Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Retained	22,698	21,208
Consumer, excluding credit card | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Retained	8,989	10,096
Consumer, excluding credit card | Mortgages | Prime mortgage | Residential real estate - PCI
Loans and Leases Receivable Disclosure [Line Items]
Retained	7,602	8,893
Consumer, excluding credit card | Mortgages | Subprime mortgage | Residential real estate - PCI
Loans and Leases Receivable Disclosure [Line Items]
Retained	2,941	3,263
Consumer, excluding credit card | Option ARMs | Residential real estate - PCI
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 12,234	$ 13,853