| Document and Entity Information | Aug. 05, 2021 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 5, 2021 |
| Entity File Number | 001-33480 |
| Entity Registrant Name | CLEAN ENERGY FUELS CORP. |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 33-0968580 |
| Entity Address, Address Line One | 4675 MacArthur Court, Suite 800 |
| Entity Address, City or Town | Newport Beach |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92660 |
| City Area Code | 949 |
| Local Phone Number | 437-1000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock |
| Trading Symbol | CLNE |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001368265 |
| Amendment Flag | false |
