GM Financial Receivables and Transactions - Commercial Finance Receivables Credit Quality Indicators (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
GM Financial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
GM Financial receivables, net of fees	$ 53,961	$ 53,900
Commercial Finance Receivables [Member] \| GM Financial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving	6,625
2020	135
2019	241
2018	113
2017	125
2016	141
2015	79
Prior	30
GM Financial receivables, net of fees	$ 7,489	$ 11,671
Percent	100.00%
Commercial Finance Receivables [Member] \| GM Financial [Member] \| Group I - Performing accounts with strong to acceptable financial metrics [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving	$ 5,989
2020	134
2019	226
2018	81
2017	102
2016	127
2015	61
Prior	8
GM Financial receivables, net of fees	$ 6,728
Percent	89.80%
Commercial Finance Receivables [Member] \| GM Financial [Member] \| Group II - Performing accounts experiencing potential weakness in financial metrics [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving	$ 388
2020	1
2019	7
2018	3
2017	21
2016	4
2015	13
Prior	22
GM Financial receivables, net of fees	$ 459
Percent	6.10%
Commercial Finance Receivables [Member] \| GM Financial [Member] \| Group III - Non-Performing accounts with inadequate paying capacity for current obligations [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving	$ 247
2020	0
2019	8
2018	29
2017	2
2016	10
2015	1
Prior	0
GM Financial receivables, net of fees	$ 297
Percent	4.00%
Commercial Finance Receivables [Member] \| GM Financial [Member] \| Group IV - Non-Performing accounts with inadequate paying capacity for current obligations and inherent weaknesses [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving	$ 1
2020	0
2019	0
2018	0
2017	0
2016	0
2015	4
Prior	0
GM Financial receivables, net of fees	$ 5
Percent	0.10%
Floorplan Advances [Member] \| Commercial Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Percent of revolving balance	97.00%

Financing Receivable, Originated Five Years before Latest Fiscal Year

No definition available.

Name:	gm_FinancingReceivableOriginatedFiveYearsbeforeLatestFiscalYear
Namespace Prefix:	gm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing Receivable, Originated, More than Six Years before Current Fiscal Year

+ References

No definition available.

+ Details

Name:	gm_FinancingReceivableOriginatedMorethanSixYearsbeforeCurrentFiscalYear
Namespace Prefix:	gm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing Receivable, Revolving, Percent of Total

+ References

No definition available.

+ Details

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

- Definition

Financing Receivable, before Allowance for Credit Loss, Percent

+ References

No definition available.

+ Details

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

- Definition

Amount of financing receivable originated four years prior to current fiscal year.

+ References

+ Details

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

- Definition

Amount of financing receivable originated in current fiscal year.

+ References

+ Details

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

- Definition

Amount of financing receivable originated in fiscal year prior to current fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919232-210447

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448

+ Details

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

- Definition

Amount of financing receivable originated three years prior to current fiscal year.

+ References

+ Details

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

- Definition

Amount of financing receivable originated two years prior to current fiscal year.

+ References

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of financing receivable that can be withdrawn, repaid and redrawn.

+ References

+ Details

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

- Definition

Amount, before allowance for credit loss, of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919230-210447

Reference 3: 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=121647567&loc=SL82922355-210448

+ Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_InternalInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SubprimeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=gm_FloorplanAdvancesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: