| Cover | Dec. 13, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Dec. 13, 2021 |
| Entity Registrant Name | ENERGY FOCUS, INC/DE |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36583 |
| Entity Tax Identification Number | 94-3021850 |
| Entity Address, Address Line One | 32000 Aurora Road Suite B |
| Entity Address, City or Town | Solon, |
| Entity Address, State or Province | OH |
| Entity Address, Postal Zip Code | 44139 |
| City Area Code | 440 |
| Local Phone Number | 715-1300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | EFOI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000924168 |
| Amendment Flag | false |
