Debt - Carrying Amount and Fair Value of Debt (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Automotive
Debt Instrument [Line Items]
Finance lease liabilities	$ 282	$ 237
Finance lease liabilities, Fair Value	299	256
Carrying Amount	17,552	17,469
Fair Value	20,890	21,576
Available under credit facility agreements(b)	$ 18,210,000	$ 18,222,000
Weighted-average interest rate on outstanding short-term debt	3.90%	3.80%
Weighted-average interest rate on outstanding long-term debt	5.60%	5.60%
Net discount and debt issuance costs	$ 529	$ 540
Automotive \| Secured Debt
Debt Instrument [Line Items]
Carrying Amount	302	303
Fair Value	321	332
Automotive \| Unsecured Debt
Debt Instrument [Line Items]
Carrying Amount	16,968	16,929
Fair Value	20,270	20,988
Automotive \| Level 1
Debt Instrument [Line Items]
Fair Value	19,112	19,826
Automotive \| Level 2
Debt Instrument [Line Items]
Fair Value	1,778	1,750
GM Financial
Debt Instrument [Line Items]
Carrying Amount	93,695	92,425
Fair Value	95,913	94,948
GM Financial \| Line of Credit
Debt Instrument [Line Items]
Aggregate borrowing capacity	6,000
GM Financial \| Secured Debt
Debt Instrument [Line Items]
Carrying Amount	39,965	39,982
Fair Value	40,292	40,380
GM Financial \| Unsecured Debt
Debt Instrument [Line Items]
Carrying Amount	53,730	52,443
Fair Value	$ 55,621	54,568
GM Financial \| Unsecured Debt \| Line of Credit \| $2.0 Billion Dollar Revolving Credit Facility
Debt Instrument [Line Items]
Debt term	364 days
Aggregate borrowing capacity	$ 2,000
GM Financial \| Level 2
Debt Instrument [Line Items]
Fair Value	94,210	92,922
GM Financial \| Level 3
Debt Instrument [Line Items]
Fair Value	$ 1,703	$ 2,026

Debt and Finance Lease Liabilities

No definition available.

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

- Definition

Finance Lease Liabilities, Fair Value Disclosure

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13433-108611

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- 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.

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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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- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918701-209980

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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=120391452&loc=d3e13212-122682

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Paragraph 1
-Subparagraph (SX 210.5-02.19(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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