GM Financial Receivables and Transactions Retail Finance Receivables Delinquencies and TDRs (Details) - GM Financial [Member] $ in Millions	Jun. 30, 2018 USD ($) score	Dec. 31, 2017 USD ($) score	Jun. 30, 2017 USD ($)
Delinquent Contracts [Abstract]
Finance receivables, individually evaluated for impairment, net of fees	$ 2,323	$ 2,250
Allowance for loan losses - TDRs	$ 313	$ 331
Retail Finance Receivables [Member]
Financing Receivable, Recorded Investment, Additional Information [Abstract]
Percentage of receivables with sub-prime credit scores	29.00%	33.00%
Sub-prime FICO score \| score	620	620
Retail finance receivables, nonaccrual status	$ 822	$ 778
Delinquent Contracts [Abstract]
Past Due Amount	$ 1,697		$ 1,583
Percent of Contractual Amount Due	4.80%		5.10%
Finance receivables, individually evaluated for impairment, net of fees	$ 2,277	2,228
Allowance for loan losses - TDRs	307	$ 328
31-to-60 days delinquent [Member] \| Retail Finance Receivables [Member]
Delinquent Contracts [Abstract]
Past Due Amount	$ 1,178		$ 1,076
Percent of Contractual Amount Due	3.30%		3.40%
Greater-than-60 days delinquent [Member] \| Retail Finance Receivables [Member]
Delinquent Contracts [Abstract]
Past Due Amount	$ 462		$ 464
Percent of Contractual Amount Due	1.30%		1.50%
Total finance receivables more than 30 days delinquent [Member] \| Retail Finance Receivables [Member]
Delinquent Contracts [Abstract]
Past Due Amount	$ 1,640		$ 1,540
Percent of Contractual Amount Due	4.60%		4.90%
In repossession [Member] \| Retail Finance Receivables [Member]
Delinquent Contracts [Abstract]
Past Due Amount	$ 57		$ 43
Percent of Contractual Amount Due	0.20%		0.20%

Financing Receivable, Recorded Investment, Additional Information [Abstract]

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- Definition

Sub-prime loans as percentage of the total loans.

+ References

No definition available.

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- Definition

The FICO score used to separate sub-prime from prime loans. The loans with a borrower that has less then this score will be considered as sub-prime.

+ References

No definition available.

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- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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- Definition

Percentage of financing receivable balance that is past due.

+ References

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

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- Definition

Recorded Investment in financing receivables that are past due at the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953401-111524

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- References

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