Contingent Liabilities and Guarantees - Guarantees (Details) $ in Millions	Sep. 30, 2020 USD ($)
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	$ 14,333
Liability Recorded	167
Written put options
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	3,284
Liability Recorded	63
Standby letters of credit
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	3,107
Liability Recorded	72
Recourse agreement with FNMA
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	5,662
Liability Recorded	23
Residential mortgage reserve
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	2,280
Liability Recorded	$ 9

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

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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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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

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