Derivative Financial Instruments - Balance Sheet Location of GM Financial Unsecured Debt (Details) - Fair Value Hedges [Member] - Long-term Debt [Member] - GM Financial [Member] - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2020 |
Dec. 31, 2019 |
|
| Derivatives, Fair Value [Line Items] | ||
| Carrying Amount of Hedged Items | $ 22,082 | $ 20,397 |
| Cumulative Amount of Fair Value Hedging Adjustments on Hedging Relationships | (539) | $ (77) |
| Interest Rate Swap [Member] | ||
| Derivatives, Fair Value [Line Items] | ||
| Loss on derivative instruments, net | $ 503 |