STOCK OPTIONS - SUMMARY OF OPTION ACTIVITY - (Details) - Stock Options - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Summary of option activity - Shares      
Outstanding at the beginning of year (in shares) 3,253,310    
Granted (in shares) 333,250    
Forfeited (in shares) (257,570)    
Exercised (in shares) (135,205)    
Outstanding at the end of period (in shares) 3,193,785 3,253,310  
Vested at the end of period (in shares) 1,811,996    
Vested and expected to vest at the end of period (in shares) 2,741,045    
Summary of option activity - Weighted Average Exercise Price      
Outstanding at the beginning of year (in dollars per shares) $ 7.47    
Granted (in dollars per shares) 6.27    
Forfeited (in dollars per shares) 8.47    
Exercised (in dollars per shares) 1.41    
Outstanding at the end of period (in dollars per shares) 7.52 $ 7.47  
Vested at the end of period (in dollars per share) 7.54    
Vested and expected to vest at the end of period (in dollars per share) $ 7.52    
Option activity disclosures      
Weighted Average Remaining Contractual Term - Outstanding 6 years 11 months 5 days    
Weighted Average Remaining Contractual Term - Vested 6 years 3 months 26 days    
Weighted Average Remaining Contractual Term - Vested and expected to vest 6 years 9 months 22 days    
Aggregate Intrinsic Value - Outstanding (in dollars) $ 571    
Aggregate Intrinsic Value - Vested (in dollars) 563    
Aggregate Intrinsic Value - Vested and expected to vest (in dollars) $ 568    
Stock Option      
Weighted average grant-date fair value of options granted $ 5.23 $ 7.37 $ 6.15
Total fair value of options vested $ 5,179 $ 5,144 $ 2,329
Total unrecognized compensation expense, related to non-vested share-based compensation arrangements $ 5,630    
Period for unrecognized compensation expense is estimated to be recognized 2 years 4 months 13 days