| Cover | Dec. 07, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Dec. 7, 2021 |
| Entity Registrant Name | Proterra Inc |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-39546 |
| Entity Tax Identification Number | 98-1551379 |
| Entity Address, Address Line One | 1815 Rollins Road |
| Entity Address, City or Town | Burlingame |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94010 |
| City Area Code | 864 |
| Local Phone Number | 438-0000 |
| Entity Information, Former Legal or Registered Name | |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | PTRA |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
| Entity Central Index Key | 0001820630 |
| Amendment Flag | false |
