Debt - Automotive and GM Financial Debt (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Automotive
Debt Instrument [Line Items]
Total debt	$ 14,386	$ 13,963
Fair value of debt	15,928	13,531
Available under credit facility agreements	$ 17,285	$ 14,167
Weighted-average interest rate on outstanding short-term debt	4.90%	6.60%
Weighted-average interest rate on outstanding long-term debt	5.40%	5.20%
Net discount and debt issuance costs	$ 540	$ 499
Automotive \| Secured Debt
Debt Instrument [Line Items]
Total debt	167	143
Automotive \| Unsecured Debt
Debt Instrument [Line Items]
Total debt	13,909	13,292
Automotive \| Level 1
Debt Instrument [Line Items]
Fair value of debt	13,628	11,693
Automotive \| Level 2
Debt Instrument [Line Items]
Fair value of debt	2,300	1,838
GM Financial
Debt Instrument [Line Items]
Total debt	88,938	90,988
Fair value of debt	90,399	90,391
GM Financial \| Secured Debt
Debt Instrument [Line Items]
Total debt	39,959	42,835
Fair value of debt	40,160	42,835
GM Financial \| Unsecured Debt
Debt Instrument [Line Items]
Total debt	48,979	48,153
Fair value of debt	50,239	47,556
GM Financial \| Level 2
Debt Instrument [Line Items]
Fair value of debt	88,481	88,305
GM Financial \| Level 3
Debt Instrument [Line Items]
Fair value of debt	1,918	2,086
Finance Lease Liabilities \| Automotive
Debt Instrument [Line Items]
Total debt	$ 310	$ 528

Amount of short-term and long-term debt and lease obligation.

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

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

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