SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 2) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost, Total	$ 5,222	$ 3,293	$ 9,326	$ 6,589
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost, Total	2,381	1,742	4,381	2,992
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost, Total	$ 2,841	$ 1,551	$ 4,945	$ 3,597

$ 5,222

$ 3,293

$ 9,326

$ 6,589

2,381

1,742

4,381

2,992

$ 2,841

$ 1,551

$ 4,945

$ 3,597