Derivative Financial Instruments - Impact of Derivatives on Consolidated Statement of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Additional compensation and employee benefits expense due to accelerated vesting	$ 249
Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	205	$ 542	$ 505
Derivatives not designated as hedging instruments | Foreign exchange contracts | Trading services
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	662	686	612
Derivatives not designated as hedging instruments | Interest-rate contracts | Trading services
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	(7)	(2)	1
Derivatives not designated as hedging instruments | Interest-rate contracts | Processing fees and other revenue
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	1	0	0
Derivatives not designated as hedging instruments | Credit derivative contracts | Trading services
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	(1)	(1)	1
Derivatives not designated as hedging instruments | Credit derivative contracts | Processing fees and other revenue
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	0	0	(1)
Derivatives not designated as hedging instruments | Other derivative contracts | Trading services
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	(2)	8	(2)
Derivatives not designated as hedging instruments | Other derivative contracts | Compensation and employee benefits
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	$ (448)	$ (149)	$ (106)