Derivative Instruments and Hedging Activities - Net Gains (Losses) Related to Derivatives Designated as Cash Flow Hedges and Net Investment Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in AOCI	$ 277	$ 367	$ 360
Other Non-Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gains recognized in earnings	85	75	95
Cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in AOCI	(3)	284	228
Gains (losses) reclassified from AOCI into earnings	195	174	108
Net derivative gains recognized in earnings	191	176	109
Cash flow hedges | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in AOCI	(6)	301	251
Cash flow hedges | Interest rate contracts | Interest Income (Expense)
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reclassified from AOCI into earnings	192	190	131
Cash flow hedges | Interest rate contracts | Other Non-Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings due to ineffectiveness	(4)	2	1
Cash flow hedges | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in AOCI	3	(17)	(23)
Cash flow hedges | Foreign exchange contracts | Other Non-Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reclassified from AOCI into earnings	3	(16)	(23)
Net investment hedges | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in AOCI	$ 280	$ 83	$ 132