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Significant Accounting Policies (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018	Jan. 01, 2018
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 Return Adjustment Is Amortized		4 years
Percentage of Non-US Pension Benefit Obligation Related to Canada, United Kingdom and Germany		92.00%
Income Taxes [Abstract]
Valuation Allowance Methodology Number Of Years Utilized		3 years
Minimum Percentage Threshold To Recognize The Tax Benefit For Uncertain Tax Positions		50.00%
Foreign Currency Transactions and Translation [Abstract]
Foreign currency transaction and remeasurement losses		$ 168	$ 52	$ 229
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Adoption of accounting standards (Note 2)		(1,144)
Automotive Selling, General and Administrative Expense [Member]
Advertising and Promotion Expenditures [Abstract]
Advertising and Promotion Expenditures		4,000	4,300	4,600
Automotive Cost of Sales [Member]
Research and Development Expenditures [Abstract]
Research and Development Expenditures		$ 7,800	$ 7,300	$ 6,600
GM Financial [Member] | Minimum [Member] | Vehicles [Member]
Equipment on Operating Leases, net [Abstract]
Leasing Arrangements, Term of Contract		2 years
GM Financial [Member] | Maximum [Member] | Vehicles [Member]
Equipment on Operating Leases, net [Abstract]
Leasing Arrangements, Term of Contract		5 years
GM Financial [Member] | Retail Finance Receivables [Member]
Revenue Recognition [Abstract]
Period Past Due Threshold for Suspending Accrual of Finance Charge Income		60 days
Finance Receivables [Abstract]
Period Past Due Threshold for Charge Off of Finance Receivables		120 days
GM Financial [Member] | Commercial Finance Receivables [Member]
Revenue Recognition [Abstract]
Period Past Due Threshold for Suspending Accrual of Finance Charge Income		90 days
Automotive [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue Recognition, Separate and Bundled Services, Term		3 years
Automotive [Member] | Vehicles [Member]
Equipment on Operating Leases, net [Abstract]
Leasing Arrangements, Term of Contract		7 months
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards (Note 2)						$ 182
Accounting Standards Update 2017-12 and Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards (Note 2)					$ 108
Forecast [Member] | Noncancelable Operating Lease Assets [Member] | Accounting Standards Update 2016-02 [Member]
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Adoption of accounting standards (Note 2)	$ 1,000
Forecast [Member] | Noncancelable Operating Lease Obligations [Member] | Accounting Standards Update 2016-02 [Member]
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Adoption of accounting standards (Note 2)	$ 1,000

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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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Maximum period past due before the accrual of finance charge income is suspended.

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Maximum original maturity period threshold for securities that are considered highly liquid. 'P90D' represents the reported fact of 90 days.

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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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Revenue Recognition, Separate and Bundled Services, Term

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Number of rolling years of actual and current year results utilized as the primary measure of cumulative losses for purposes of establishing the deferred tax asset valuation allowance.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Term of lessor's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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The total expense recognized in the period for promotion, public relations, and brand or product advertising.

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Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

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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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Threshold period past due for financing receivable to write off as uncollectible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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