Debt - Narrative (Details) - USD ($) $ in Billions	1 Months Ended	3 Months Ended
Apr. 30, 2020	Mar. 31, 2020
Unsecured Debt [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Debt term		3 years
Aggregate borrowing capacity		$ 3.0
Proceeds borrowed		2.0
Dividend restriction covenant, amount outstanding		5.0
Unsecured Debt [Member] \| Line of Credit [Member] \| Five Year Revolving Credit Facility Due 2023 [Member]
Debt Instrument [Line Items]
Aggregate borrowing capacity		10.5
Proceeds borrowed		$ 10.5
Unsecured Debt [Member] \| Line of Credit [Member] \| Three Year Revolving Credit Facility April 2021 [Member]
Debt Instrument [Line Items]
Debt term		3 years
Aggregate borrowing capacity		$ 4.0
Proceeds borrowed		$ 3.4
Unsecured Debt [Member] \| Line of Credit [Member] \| Five Year Revolving Credit Facility April 2020 [Member]
Debt Instrument [Line Items]
Debt term		5 years
GM Financial [Member] \| Unsecured Debt [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Weighted average interest rate (percent)		4.47%
GM Financial [Member] \| Unsecured Debt [Member] \| Line of Credit [Member] \| $2.0 Billion Dollar Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt term		364 days
Aggregate borrowing capacity		$ 2.0
GM Financial [Member] \| Unsecured Debt [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Weighted-average interest rate on outstanding long-term debt		3.33%
Principal amount		$ 2.1
Weighted average interest rate (percent)		2.09%
GM Financial [Member] \| Secured Debt [Member] \| Notes Payable, Other Payables [Member] \| Securitization notes payable [Member]
Debt Instrument [Line Items]
Weighted-average interest rate on outstanding long-term debt		2.59%
Principal amount		$ 4.6
Weighted average interest rate (percent)		1.95%
Subsequent Event [Member] \| Unsecured Debt [Member] \| Line of Credit [Member] \| Three Year Revolving Credit Facility April 2022 [Member]
Debt Instrument [Line Items]
Aggregate borrowing capacity	$ 3.6
Subsequent Event [Member] \| GM Financial [Member] \| Unsecured Debt [Member] \| Line of Credit [Member] \| $2.0 Billion Dollar Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt term	364 days
Maximum [Member] \| GM Financial [Member] \| Unsecured Debt [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt term		4 years

Line of Credit Facility, Covenant Terms, Dividend Restrictions, Amount Outstanding

No definition available.

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Namespace Prefix:	gm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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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

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Period Type:	instant

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

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

- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

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