Variable Interest Entities - Loan Delinquencies and Net Charge-offs (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Securitized loans
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
90 days past due	$ 13,352	$ 4,449
Net liquidation losses	421	1,556
Securitized loans \| Commercial and other
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
90 days past due	5,958	187
Net liquidation losses	30	445
Nonconsolidated entities
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
Securitized assets	145,770	143,102
Nonconsolidated entities \| Commercial and other
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
Securitized assets	92,351	80,878
Prime/Alt-A and option ARMs \| Securitized loans \| Residential mortgage
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
90 days past due	4,988	2,449
Net liquidation losses	212	579
Prime/Alt-A and option ARMs \| Nonconsolidated entities \| Residential mortgage
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
Securitized assets	41,265	48,734
Subprime \| Securitized loans \| Residential mortgage
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
90 days past due	2,406	1,813
Net liquidation losses	179	532
Subprime \| Nonconsolidated entities \| Residential mortgage
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
Securitized assets	$ 12,154	$ 13,490

Amount of transferred financial assets in which the transferor has continuing involvement with the assets underlying the transaction that have been derecognized. Continuing involvement includes, but is not limited to, servicing, recourse, and restrictions on transferor's interests in transferred financial assets.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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- Definition

Amount of financing receivable 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (c)
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524

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-Topic 326
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-Section 55
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- References

No definition available.

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- Definition

Amount of credit loss after recoveries for transferred financial assets that continue to be recognized in the statement of financial position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 50
-Paragraph 4
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-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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