| Cover Page Cover Page | Jul. 25, 2019 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Jul. 25, 2019 |
| Entity Registrant Name | CARBONITE INC |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-35264 |
| Entity Tax Identification Number | 33-1111329 |
| Entity Address, Address Line One | Two Avenue de Lafayette |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02111 |
| City Area Code | 617 |
| Local Phone Number | 587-1100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | CARB |
| Security Exchange Name | NASDAQ |
| Entity Central Index Key | 0001340127 |
| Amendment Flag | false |
