GM Financial Receivables and Transactions - Retail Finance Receivables Delinquencies and TDRs (Details) - GM Financial [Member] $ in Millions	Sep. 30, 2019 USD ($) score	Dec. 31, 2018 USD ($) score
Delinquent Contracts [Abstract]
Finance receivables, individually evaluated for impairment, net of fees	$ 2,430	$ 2,389
Allowance for loan losses - TDRs	$ 348	$ 325
Retail Finance Receivables [Member]
Financing Receivable, Recorded Investment, Additional Information [Abstract]
Percentage of receivables with sub-prime credit scores	24.00%	25.00%
Sub-prime FICO score \| score	620	620
Retail finance receivables, nonaccrual status	$ 853	$ 888
Delinquent Contracts [Abstract]
Past Due Amount	$ 1,814	$ 1,853
Percent of Contractual Amount Due	4.30%	4.90%
Finance receivables, individually evaluated for impairment, net of fees	$ 2,390	$ 2,348
Allowance for loan losses - TDRs	337	321
31-to-60 days delinquent [Member] \| Retail Finance Receivables [Member]
Delinquent Contracts [Abstract]
Past Due Amount	$ 1,252	$ 1,302
Percent of Contractual Amount Due	3.00%	3.50%
Greater-than-60 days delinquent [Member] \| Retail Finance Receivables [Member]
Delinquent Contracts [Abstract]
Past Due Amount	$ 514	$ 498
Percent of Contractual Amount Due	1.20%	1.30%
Total finance receivables more than 30 days delinquent [Member] \| Retail Finance Receivables [Member]
Delinquent Contracts [Abstract]
Past Due Amount	$ 1,766	$ 1,800
Percent of Contractual Amount Due	4.20%	4.80%
In repossession [Member] \| Retail Finance Receivables [Member]
Delinquent Contracts [Abstract]
Past Due Amount	$ 48	$ 53
Percent of Contractual Amount Due	0.10%	0.10%

Financing Receivable, Recorded Investment, Additional Information [Abstract]

No definition available.

Name:	gm_FinancingReceivableRecordedInvestmentAdditionalInformationAbstract
Namespace Prefix:	gm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Sub-prime loans as percentage of the total loans.

+ References

No definition available.

+ Details

Name:	gm_PercentageofSubPrimeLoans
Namespace Prefix:	gm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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.

+ Details

Name:	gm_SubprimeFICOScore
Namespace Prefix:	gm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of financing receivable balance that is past due.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivablePercentPastDue1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of financing receivable on nonaccrual status.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of financing receivable past due.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953401-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRecordedInvestmentAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	gm_BusinessGroupAxis=gm_GmFinancialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=gm_FinancingReceivables31to60DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=gm_FinancingReceivablesGreaterthan60DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=gm_FinancingReceivablesGreaterthan30DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=gm_FinancingReceivablesInRepossessionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: