| Cover | Feb. 12, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 12, 2021 |
| Entity File Number | 001-37474 |
| Entity Registrant Name | Conformis, Inc |
| Entity Central Index Key | 0001305773 |
| Entity Tax Identification Number | 56-2463152 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 600 Technology Park Drive |
| Entity Address, City or Town | Billerica |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 01821 |
| City Area Code | 781 |
| Local Phone Number | 345-9001 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.00001 par value per share |
| Trading Symbol | CFMS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
