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Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue Recognition [Abstract]
Revenue recognition term of separate and bundled services	7 years
Cash Equivalents [Abstract]
Maximum maturity period for highly liquid securities	90 days
Pension and Other Postretirement Plans [Abstract]
Percentage recognized as pension expense in the first year	60.00%
Percentage of pension expense recognized in each of the next four years	10.00%
Subsequent period over which pension expense adjustment is amortized	4 years
Percentage of non-US pension benefit obligations related to Canada, United Kingdom and Germany	93.00%
Income Taxes [Abstract]
Number of years used for valuation allowance methodology	3 years
Minimum threshold to recognize the tax benefit for uncertain tax positions	50.00%
Foreign Currency Transactions and Translation [Abstract]
Foreign currency remeasurement and transaction (gains) losses	$ 203	$ (85)	$ 168
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Stockholders' equity	(49,677)	(45,957)	(42,777)	$ (36,200)
Cumulative Effect, Period of Adoption, Adjustment
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Stockholders' equity		660		$ 1,144
Automotive Selling, General and Administrative Expense
Advertising and Promotion Expenditures [Abstract]
Advertising and promotion expenditures	2,700	3,700	4,000
Automotive Cost of Sales
Research and Development Expenditures [Abstract]
Research and development expenditures	$ 6,200	6,800	$ 7,800
GM Financial | Minimum | Vehicles
Equipment on Operating Leases, net [Abstract]
Term of leasing arrangements	2 years
GM Financial | Maximum | Vehicles
Equipment on Operating Leases, net [Abstract]
Term of leasing arrangements	5 years
GM Financial | Retail Finance Receivables
Revenue Recognition [Abstract]
Period past due threshold for suspending accrual of finance charge income	60 days
GM Financial | Commercial Finance Receivables
Revenue Recognition [Abstract]
Period past due threshold for suspending accrual of finance charge income	90 days
Automotive | Vehicles
Equipment on Operating Leases, net [Abstract]
Term of leasing arrangements	7 months
Financing Receivable, Allowance for Credit Loss | Accounting Standards Update 2016-13 | GM Financial | Cumulative Effect, Period of Adoption, Adjustment
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Stockholders' equity		801
Retained Earnings | Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Stockholders' equity		660
Retained Earnings | Accounting Standards Update 2016-13 | GM Financial | Cumulative Effect, Period of Adoption, Adjustment
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Stockholders' equity		$ 643

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Equipment on Operating Leases, net [Abstract]

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The aggregate realized and unrealized foreign currency transaction gain or loss, net (pretax) or remeasurement gain or loss, net (pretax) included in determining net income for the reporting period. Represents the aggregate of gains or losses, net, on foreign currency transactions that are unsettled as of the balance sheet date, which is therefore an adjustment to reconcile income or loss from continuing operations to net cash provided by or used in continuing operations. Also includes the gains or losses associated with remeasuring foreign currency denominated entities into the functional currency of those entities. Excludes foreign currency transactions designated as hedges of net investment in a foreign entity.

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Percentage of benefit obligation for pension plans of Canada, the United Kingdom and Germany to the total non- U.S. pension benefit obligation.

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An expected return on plan asset methodology is utilized to calculate future pension expense for certain significant funded benefit plans. A market-related value of plan assets methodology is also utilized that averages gains and losses on the plan assets over a period of years to determine future pension expense. The element represents the percentage recognized of the difference between the fair value of assets and the expected calculated value in each of the next four years after the first year.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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