Variable Interest Entities and Securitization Activities (Transfers of Assets with Continuing Involvement 2) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Variable Interest Entity
Derivative assets	$ 33,148	$ 30,813
Derivative liabilities	25,986	26,695
SPE
Variable Interest Entity
Retained interests	1,252	988
Interests purchased in the secondary market (fair value)	271	619
Derivative assets	191	227
Derivative liabilities	119	85
SPE \| Investment Grade
Variable Interest Entity
Retained interests	836	411
Interests purchased in the secondary market (fair value)	183	533
SPE \| Non-investment Grade
Variable Interest Entity
Retained interests	416	577
Interests purchased in the secondary market (fair value)	88	86
SPE \| Level 2
Variable Interest Entity
Retained interests	844	429
Interests purchased in the secondary market (fair value)	234	588
Derivative assets	50	78
Derivative liabilities	114	81
SPE \| Level 2 \| Investment Grade
Variable Interest Entity
Retained interests	831	407
Interests purchased in the secondary market (fair value)	182	531
SPE \| Level 2 \| Non-investment Grade
Variable Interest Entity
Retained interests	13	22
Interests purchased in the secondary market (fair value)	52	57
SPE \| Level 3
Variable Interest Entity
Retained interests	408	559
Interests purchased in the secondary market (fair value)	37	31
Derivative assets	141	149
Derivative liabilities	5	4
SPE \| Level 3 \| Investment Grade
Variable Interest Entity
Retained interests	5	4
Interests purchased in the secondary market (fair value)	1	2
SPE \| Level 3 \| Non-investment Grade
Variable Interest Entity
Retained interests	403	555
Interests purchased in the secondary market (fair value)	$ 36	$ 29

Fair value of interests purchased in the secondary market

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Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section 55
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Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
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-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226008-175313

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- Definition

Fair value portion of interest continued to be held by a transferor after transferring financial assets to a third party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
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+ References

No definition available.

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