COMMITMENTS AND CONTINGENCIES - Minimum Annual Lease Commitments (Details)
$ in Thousands
1 Months Ended 12 Months Ended
Mar. 31, 2015
ft²
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Lease        
Rent-free term   2 months    
Aggregate minimum annual lease commitments under non cancellable operating lease        
2017   $ 226    
2018   234    
2019   241    
2020   164    
Total minimum lease payments   865    
Rent expense under operating lease agreement        
Rent expense   182 $ 112 $ 69
Guarantees        
Restricted cash   97 $ 97  
Amendment to office and research facility operating lease        
Lease        
Square of feet of space | ft² 9,660      
Office and research facility operating lease        
Lease        
Square of feet of space | ft² 19,335      
Term of lease extension option 5 years      
Stand-by letter of credit        
Guarantees        
Restricted cash   $ 97