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Derivative Instruments and Other Financial Instruments Used For Hedging - Notional Amounts and Fair Value Amounts of Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Derivative Instruments and Other Financial Instruments
Notional Amount	$ 201,729		$ 201,729		$ 220,226
Assets Derivatives	1,759		1,759		2,313
Liability Derivatives	825		825		1,029
Interest rate contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	169,712		169,712		193,326
Assets Derivatives	1,356		1,356		1,890
Liability Derivatives	585		585		754
Interest rate contracts \| Cash Flow Hedges \| Designated as Hedging Instrument
Derivative Instruments and Other Financial Instruments
Notional Amount	10,000		10,000		9,509
Assets Derivatives	0		0		0
Liability Derivatives	0		0		1
Interest rate contracts \| Fair Value Hedging \| Designated as Hedging Instrument
Derivative Instruments and Other Financial Instruments
Notional Amount	2,050		2,050		0
Assets Derivatives	0		0		0
Liability Derivatives	0		0		0
Commodity derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	1		1		4
Assets Derivatives	0		0		0
Liability Derivatives	0		0		0
Foreign exchange derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	16,526		16,526		14,189
Assets Derivatives	385		385		392
Liability Derivatives	202		202		215
Equity derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	1,291		1,291		1,599
Assets Derivatives	6		6		16
Liability Derivatives	27		27		51
Other derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	295		295		51
Assets Derivatives	2		2		0
Liability Derivatives	2		2		1
Trading derivatives \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	187,825		187,825		209,169
Assets Derivatives	1,749		1,749		2,298
Liability Derivatives	816		816		1,021
Other Risk Management \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	1,854		1,854		1,548
Assets Derivatives	10		10		15
Liability Derivatives	9		9		$ 7
Net gains (losses) on derivatives included in other noninterest income	$ 11	$ (5)	$ 16	$ (28)