Significant Accounting Policies (Details) - USD ($) $ in Millions			12 Months Ended
	Jan. 01, 2020	Jan. 01, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue Recognition [Abstract]
Revenue recognition term of separate and bundled services			3 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 transaction and remeasurement losses			$ (85)	$ 168	$ 52
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Adoption of accounting standards				(1,144)
Automotive Selling, General and Administrative Expense
Advertising and Promotion Expenditures [Abstract]
Advertising and promotion expenditures			3,700	4,000	4,300
Automotive Cost of Sales
Research and Development Expenditures [Abstract]
Research and development expenditures			$ 6,800	$ 7,800	$ 7,300
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
Finance Receivables [Abstract]
Period past due threshold for charge off of finance receivables			120 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
Noncancelable Operating Lease Assets | Accounting Standards Update 2016-02
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Adoption of accounting standards		$ 1,000
Noncancelable Operating Lease Obligations | Accounting Standards Update 2016-02
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Adoption of accounting standards		$ 1,000
Forecast | Financing Receivable, Allowance for Credit Loss | Accounting Standards Update 2016-13
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Adoption of accounting standards	$ 800
Forecast | Retained Earnings | Accounting Standards Update 2016-13
Recently Adopted Accounting Standards and Accounting Standards Not Yet Adopted [Abstract]
Adoption of accounting standards	$ (600)