v3.10.0.1
SHARE-BASED COMPENSATION - RSU Activity - Summary of Change (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Number of Restricted Stock Units [Roll Forward]      
RSUs beginning 4,285,000    
RSUs awarded 1,292,000 3,064,000 1,123,000
RSUs assumed in Merger 0    
RSUs released (1,496,000) (474,000) (611,000)
RSUs forfeited (396,000) (379,000) (27,000)
RSUs ending 3,685,000 4,285,000  
Weighted Average Purchase Price RSUs $ 0    
Weighted Average Remaining Contractual Term (Years) RSUs 1 year 1 month 6 days    
Aggregate Intrinsic Value RSUs $ 20,971    
Number of RSUs vested and expected to vest 3,685,000    
Weighted Average Purchase Price of RSUs vested and expected to vest $ 0    
Weighted Average Remaining Contractual Term (Years) of RUSs vested and expected to vest 1 year 1 month 6 days    
Aggregate Intrinsic Value RSUs vested and expected to vest $ 20,971    
Number of RSUs exercisable 49,000    
Weighted Average Purchase Price of RUSs exercisable $ 0    
Weighted Average Remaining Contractual Term (Years) of RUSs exercisable 0 years    
Aggregate Intrinsic Value RSUs exercisable $ 278    
Weighted average remaining recognition period in years 1 year 10 months 24 days    
Unamortized compensation expense, net of estimated forfeitures $ 22,458