Derivative Instruments and Other Financial Instruments Used For Hedging (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	$ 145,968		$ 145,968		$ 129,600
Fair Value, Asset Derivatives	2,606		2,606		1,828
Fair Value, Liability Derivatives	2,103		2,103		1,647
Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	130,944		130,944		113,599
Fair Value, Asset Derivatives	2,259		2,259		1,750
Fair Value, Liability Derivatives	2,095		2,095		1,631
Not designated as hedging instruments | Other risk management
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	324		324		251
Fair Value, Asset Derivatives	3		3		5
Fair Value, Liability Derivatives	8		8		2
Net losses on derivatives included in other noninterest income	10	$ 2	(11)	$ 1
Interest rate derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	117,067		117,067		100,932
Fair Value, Asset Derivatives	1,629		1,629		1,002
Fair Value, Liability Derivatives	1,576		1,576		948
Interest rate derivative contracts | Cash Flow Hedges | Designated as Hedging Instrument
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	14,200		14,200		15,250
Fair Value, Asset Derivatives	330		330		68
Fair Value, Liability Derivatives	0		0		14
Interest rate derivative contracts | Fair value hedges | Designated as Hedging Instrument
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	500		500		500
Fair Value, Asset Derivatives	14		14		5
Fair Value, Liability Derivatives	0		0		0
Commodity derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	3,482		3,482		3,775
Fair Value, Asset Derivatives	229		229		409
Fair Value, Liability Derivatives	188		188		369
Foreign exchange derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	7,472		7,472		5,541
Fair Value, Asset Derivatives	221		221		117
Fair Value, Liability Derivatives	150		150		93
Equity Derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	2,923		2,923		3,351
Fair Value, Asset Derivatives	180		180		222
Fair Value, Liability Derivatives	$ 181		$ 181		$ 221