Finance Receivables and Loans, Net (Finance receivables and loans redefaulted during the period) (Details) - Consumer portfolio segment $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable
Financing receivable, modifications, subsequent default, number of loans	2,816	1,164
Financing receivable, modifications, subsequent default, gross carrying value	$ 33	$ 13
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 20	$ 9
Automotive loan
Accounts, Notes, Loans and Financing Receivable
Financing receivable, modifications, subsequent default, number of loans	2,814	1,164
Financing receivable, modifications, subsequent default, gross carrying value	$ 33	$ 13
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 20	$ 9
Mortgage - Legacy
Accounts, Notes, Loans and Financing Receivable
Financing receivable, modifications, subsequent default, number of loans	2	0
Financing receivable, modifications, subsequent default, gross carrying value	$ 0	$ 0
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 0	$ 0

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Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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- Definition

Reflects the amount of the write-down related to a troubled debt restructuring.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18845-111554

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