Derivative Instruments and Other Financial Instruments Used For Hedging (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Derivative Instruments and Other Financial Instruments
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		$ 177
Derivative Notional Amount	$ 189,724		$ 189,724		$ 132,093
Gross Amounts of Recognized Assets/Liabilities	2,408		2,408		1,839
Gross Amounts of Recognized Assets/Liabilities	1,991		1,991		1,649
Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	167,568		167,568		113,695
Gross Amounts of Recognized Assets/Liabilities	2,155		2,155		1,750
Gross Amounts of Recognized Assets/Liabilities	1,977		1,977		1,631
Not designated as hedging instruments | Other risk management
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	5,993		5,993		2,107
Gross Amounts of Recognized Assets/Liabilities	19		19		14
Gross Amounts of Recognized Assets/Liabilities	8		8		2
Net losses on derivatives included in other noninterest income	(2)	6	(37)	$ 4
Cash Flow Hedges
Derivative Instruments and Other Financial Instruments
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(60)	177	341	286
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	43	46	127	118
Interest rate derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	153,568		153,568		100,991
Gross Amounts of Recognized Assets/Liabilities	1,598		1,598		1,002
Gross Amounts of Recognized Assets/Liabilities	1,545		1,545		948
Interest rate derivative contracts | Cash Flow Hedges
Derivative Instruments and Other Financial Instruments
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(60)	177		286
Interest rate derivative contracts | Cash Flow Hedges | Designated as Hedging Instrument
Derivative Instruments and Other Financial Instruments
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net			341
Derivative Notional Amount	15,663		15,663		15,791
Gross Amounts of Recognized Assets/Liabilities	225		225		70
Gross Amounts of Recognized Assets/Liabilities	6		6		16
Interest rate derivative contracts | Fair value hedges | Designated as Hedging Instrument
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	500		500		500
Gross Amounts of Recognized Assets/Liabilities	9		9		5
Gross Amounts of Recognized Assets/Liabilities	0		0		0
Commodity derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	3,160		3,160		3,775
Gross Amounts of Recognized Assets/Liabilities	189		189		409
Gross Amounts of Recognized Assets/Liabilities	148		148		369
Foreign exchange derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	7,235		7,235		5,541
Gross Amounts of Recognized Assets/Liabilities	196		196		117
Gross Amounts of Recognized Assets/Liabilities	112		112		93
Equity Derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	2,661		2,661		3,351
Gross Amounts of Recognized Assets/Liabilities	171		171		222
Gross Amounts of Recognized Assets/Liabilities	171		171		221
Other derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	944		944		$ 37
Gross Amounts of Recognized Assets/Liabilities	1		1
Gross Amounts of Recognized Assets/Liabilities	1		1
Interest income | Interest rate derivative contracts | Cash Flow Hedges
Derivative Instruments and Other Financial Instruments
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	43	47	127	120
Interest expense | Interest rate derivative contracts | Cash Flow Hedges
Derivative Instruments and Other Financial Instruments
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	(1)	0	(2)
Other Expense | Interest rate derivative contracts | Cash Flow Hedges
Derivative Instruments and Other Financial Instruments
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net			1	2
Maximum | Other Expense | Interest rate derivative contracts | Cash Flow Hedges
Derivative Instruments and Other Financial Instruments
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0	$ 1	$ 1	$ 2