Finance Receivables and Loans, Net (Finance receivables and loans redefaulted during the period) (Details) - Consumer portfolio segment $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable
Financing receivable, modifications, subsequent default, number of loans	10,072	7,215	9,713
Financing receivable, modifications, subsequent default, gross carrying value	$ 104	$ 81	$ 111
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 71	$ 52	$ 73
Automotive loan
Accounts, Notes, Loans and Financing Receivable
Financing receivable, modifications, subsequent default, number of loans	10,070	7,215	9,711
Financing receivable, modifications, subsequent default, gross carrying value	$ 104	$ 81	$ 111
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 71	$ 52	$ 73
Mortgage Finance operations
Accounts, Notes, Loans and Financing Receivable
Financing receivable, modifications, subsequent default, number of loans	1
Financing receivable, modifications, subsequent default, gross carrying value	$ 0
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 0
Mortgage - Legacy
Accounts, Notes, Loans and Financing Receivable
Financing receivable, modifications, subsequent default, number of loans	1		2
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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Reflects the amount of the write-down related to a troubled debt restructuring.

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

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