Finance Receivables and Loans, Net (Finance receivables and loans redefaulted during the period) (Details) - Consumer portfolio segment $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Consumer loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, modifications, subsequent default, number of loans	9,713	8,832	7,804
Financing receivable, modifications, subsequent default, gross carrying value	$ 111	$ 103	$ 94
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 73	$ 71	$ 56
Automobile loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, modifications, subsequent default, number of loans	9,711	8,829	7,800
Financing receivable, modifications, subsequent default, gross carrying value	$ 111	$ 102	$ 94
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 73	$ 71	$ 56
Mortgage Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, modifications, subsequent default, number of loans		1
Financing receivable, modifications, subsequent default, gross carrying value		$ 1
Financing receivables, impaired, troubled debt restructuring, charge-off amount		$ 0
Mortgage - Legacy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, modifications, subsequent default, number of loans	2	2	4
Financing receivable, modifications, subsequent default, gross carrying value	$ 0	$ 0	$ 0
Financing receivables, impaired, troubled debt restructuring, charge-off amount	$ 0	$ 0	$ 0

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Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

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Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

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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
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