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
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivative Instruments and Other Financial Instruments
Notional Amount	$ 312,911		$ 201,094
Assets Derivatives	1,025		871
Liability Derivatives	705		804
Interest rate derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	297,213		189,478
Assets Derivatives	713		531
Liability Derivatives	517		600
Interest rate derivative contracts \| Cash Flow Hedges \| Designated as Hedging Instrument
Derivative Instruments and Other Financial Instruments
Notional Amount	4,116		674
Assets Derivatives	20		6
Liability Derivatives	0		0
Commodity derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	273		336
Assets Derivatives	18		25
Liability Derivatives	13		18
Foreign exchange derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	8,801		8,475
Assets Derivatives	251		260
Liability Derivatives	157		168
Equity derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	284		300
Assets Derivatives	12		22
Liability Derivatives	12		13
Other derivative contracts \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	120		127
Assets Derivatives	1		0
Liability Derivatives	1		0
Trading derivatives \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	306,691		198,716
Assets Derivatives	995		838
Liability Derivatives	700		799
Other Risk Management \| Not designated as hedging instruments
Derivative Instruments and Other Financial Instruments
Notional Amount	2,104		1,704
Assets Derivatives	10		27
Liability Derivatives	5		$ 5
Net gains (losses) on derivatives included in other noninterest income	$ (9)	$ 51

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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No definition available.

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