v3.10.0.1
NET LOSS PER SHARE - Narrative (Details) - shares
Sep. 30, 2018
Jun. 30, 2018
Dec. 31, 2017
Oct. 12, 2017
Sep. 30, 2017
Temporary Equity [Line Items]          
Redeemable convertible preferred stock, outstanding (in shares)   0 0    
Redeemable Convertible Preferred Stock          
Temporary Equity [Line Items]          
Redeemable convertible preferred stock, authorized (in shares)       7,000,000  
Redeemable convertible preferred stock, outstanding (in shares)         3,649,475
Conversion ratio 1