Automotive and GM Financial Debt (Details) - USD ($) $ in Millions |
Jun. 30, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Automotive [Member] | ||
| Debt Instrument [Line Items] | ||
| Carrying Amount | $ 13,819 | $ 13,502 |
| Fair Value | 14,362 | 15,088 |
| Automotive [Member] | Level 1 [Member] | ||
| Debt Instrument [Line Items] | ||
| Fair Value | 12,042 | 13,202 |
| Automotive [Member] | Level 2 [Member] | ||
| Debt Instrument [Line Items] | ||
| Fair Value | 2,320 | 1,886 |
| GM Financial [Member] | ||
| Debt Instrument [Line Items] | ||
| Carrying Amount | 84,440 | 80,717 |
| Fair Value | 84,869 | 81,937 |
| GM Financial [Member] | Secured Debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Carrying Amount | 39,083 | 39,887 |
| Fair Value | 39,024 | 39,948 |
| GM Financial [Member] | Unsecured Debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Carrying Amount | 45,357 | 40,830 |
| Fair Value | 45,845 | 41,989 |
| GM Financial [Member] | Level 2 [Member] | ||
| Debt Instrument [Line Items] | ||
| Fair Value | 82,604 | 79,623 |
| GM Financial [Member] | Level 3 [Member] | ||
| Debt Instrument [Line Items] | ||
| Fair Value | $ 2,265 | $ 2,314 |