Loans - Net Gains and Losses on Sale (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Loans and Leases Receivable Disclosure [Line Items]
Total net gains/(losses) on sales of loans (including lower of cost or fair value adjustments)	$ 84	$ 87	$ 185	$ 153
Consumer, excluding credit card
Loans and Leases Receivable Disclosure [Line Items]
Total net gains/(losses) on sales of loans (including lower of cost or fair value adjustments)	86	84	177	126
Credit card
Loans and Leases Receivable Disclosure [Line Items]
Total net gains/(losses) on sales of loans (including lower of cost or fair value adjustments)	(7)	0	9	0
Wholesale
Loans and Leases Receivable Disclosure [Line Items]
Total net gains/(losses) on sales of loans (including lower of cost or fair value adjustments)	$ 5	$ 3	$ (1)	$ 27