Sales of Receivables and Servicing Rights - Sensitivity of the Current Fair Value of Residual Cash Flows to Immediate 10%, 20% and 50% Adverse Changes in Assumptions (Details) $ in Millions	9 Months Ended
Sep. 30, 2020 USD ($) bps
Fixed Rate Residential Mortgage
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption
Fair Value	$ 652
Weighted- Average Life (in years)	4 years 1 month 6 days
Prepayment Speed Assumption, Rate (as a percent)	18.20%
Prepayment Speed Assumption, Impact of Adverse Change on Fair Value 10%	$ (22)
Prepayment Speed Assumption, Impact of Adverse Change on Fair Value 20%	(42)
Prepayment Speed Assumption, Impact of Adverse Change on Fair Value 50%	$ (94)
OAS Speed Assumption, OAS (bps) \| bps	918
OAS Spread Assumption, Impact of Adverse Change on Fair Value 10%	$ (18)
OAS Spread Assumption, Impact of Adverse Change on Fair Value 20%	(35)
Adjustable Rate Residential Mortgage
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption
Fair Value	$ 8
Weighted- Average Life (in years)	3 years 8 months 12 days
Prepayment Speed Assumption, Rate (as a percent)	21.20%
Prepayment Speed Assumption, Impact of Adverse Change on Fair Value 10%	$ (1)
Prepayment Speed Assumption, Impact of Adverse Change on Fair Value 20%	(1)
Prepayment Speed Assumption, Impact of Adverse Change on Fair Value 50%	$ (2)
OAS Speed Assumption, OAS (bps) \| bps	938
OAS Spread Assumption, Impact of Adverse Change on Fair Value 10%	$ 0
OAS Spread Assumption, Impact of Adverse Change on Fair Value 20%	$ 0

Option adjusted spread basis points.

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- Definition

Weighted average life of securitized assets regardless of when the transfer occurred, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

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- Definition

Estimated rate of prepayment of principal on financial assets regardless of when the transfer occurred.

+ References

+ Details

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- Definition

The carrying amount (fair value) as of the balance sheet date of the transferor's interests in transferred financial assets (typically securitized receivables, generally not involved in the collection of principal) following transfer of significant portions of such financial instruments to other parties. Such interests could be ancillary cash flows and interest-only strips.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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- Definition

The hypothetical financial impact of a 10 percent adverse change of the discount rate on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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- Definition

The hypothetical financial impact of a 10 percent adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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- Definition

The hypothetical financial impact of a 20 percent adverse change of the discount rate on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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- Definition

The hypothetical financial impact of a 20 percent adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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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

The hypothetical financial impact of a specified adverse percentage change in prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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