Derivative Instruments and Other Financial Instruments Used For Hedging - Notional and Fair Value Amounts (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments and Other Financial Instruments
Notional Amount	$ 177,428	$ 132,093
Fair Value, Asset Derivatives	1,626	1,839
Fair Value, Liability Derivatives	1,684	1,649
Not designated as hedging instruments \| Trading
Derivative Instruments and Other Financial Instruments
Notional Amount	160,424	113,695
Fair Value, Asset Derivatives	1,601	1,750
Fair Value, Liability Derivatives	1,395	1,631
Not designated as hedging instruments \| Other risk management
Derivative Instruments and Other Financial Instruments
Notional Amount	1,045	2,107
Fair Value, Asset Derivatives	3	14
Fair Value, Liability Derivatives	90	2
Interest rate contracts \| Not designated as hedging instruments \| Trading
Derivative Instruments and Other Financial Instruments
Notional Amount	149,229	100,991
Fair Value, Asset Derivatives	1,074	1,002
Fair Value, Liability Derivatives	988	948
Interest rate contracts \| Cash flow hedges \| Designated as hedging instrument
Derivative Instruments and Other Financial Instruments
Notional Amount	15,459	15,791
Fair Value, Asset Derivatives	19	70
Fair Value, Liability Derivatives	199	16
Interest rate contracts \| Fair value hedges \| Designated as hedging instrument
Derivative Instruments and Other Financial Instruments
Notional Amount	500	500
Fair Value, Asset Derivatives	3	5
Fair Value, Liability Derivatives	0	0
Commodity contracts \| Not designated as hedging instruments \| Trading
Derivative Instruments and Other Financial Instruments
Notional Amount	2,825	3,775
Fair Value, Asset Derivatives	145	409
Fair Value, Liability Derivatives	112	369
Foreign exchange contracts \| Not designated as hedging instruments \| Trading
Derivative Instruments and Other Financial Instruments
Notional Amount	5,981	5,541
Fair Value, Asset Derivatives	217	117
Fair Value, Liability Derivatives	131	93
Equity contracts \| Not designated as hedging instruments \| Trading
Derivative Instruments and Other Financial Instruments
Notional Amount	2,385	3,351
Fair Value, Asset Derivatives	165	222
Fair Value, Liability Derivatives	164	221
Other derivative contracts \| Not designated as hedging instruments \| Trading
Derivative Instruments and Other Financial Instruments
Notional Amount	4	37
Fair Value, Asset Derivatives	0	0
Fair Value, Liability Derivatives	$ 0	$ 0

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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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ 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=56946850&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=51825145&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=51814546&loc=SL51823488-111719

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- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ 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=51814546&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
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959

Reference 4: 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=51825145&loc=SL20226000-175313

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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