Derivative Instruments and Other Financial Instruments Used For Hedging (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	$ 95,923		$ 95,923		$ 71,679
Fair Value, Asset Derivatives	2,071		2,071		1,799
Fair Value, Liability Derivatives	1,770		1,770		1,624
Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	81,748		81,748		61,143
Fair Value, Asset Derivatives	1,860		1,860		1,761
Fair Value, Liability Derivatives	1,767		1,767		1,617
Not designated as hedging instruments | Other risk management
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	275		275		286
Fair Value, Asset Derivatives	3		3		2
Fair Value, Liability Derivatives	3		3		3
Net losses on derivatives included in other noninterest income	1	$ (1)	1	$ 1
Interest rate derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	68,580		68,580		46,944
Fair Value, Asset Derivatives	1,135		1,135		933
Fair Value, Liability Derivatives	1,076		1,076		830
Interest rate derivative contracts | Cash Flow Hedges | Designated as Hedging Instrument
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	13,400		13,400		9,750
Fair Value, Asset Derivatives	197		197		34
Fair Value, Liability Derivatives	0		0		4
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	11		11		2
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	4,239		4,239		4,741
Fair Value, Asset Derivatives	432		432		422
Fair Value, Liability Derivatives	420		420		408
Foreign exchange derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	5,472		5,472		5,661
Fair Value, Asset Derivatives	111		111		106
Fair Value, Liability Derivatives	90		90		80
Equity Derivative contracts | Not designated as hedging instruments | Trading derivatives
Derivative Instruments and Other Financial Instruments
Derivative Notional Amount	3,457		3,457		3,797
Fair Value, Asset Derivatives	182		182		300
Fair Value, Liability Derivatives	$ 181		$ 181		$ 299