ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
ACCRUED EXPENSES
Accrued Payroll and Employee Benefits	$ 7,132	$ 5,601
Accrued Research and Development Contract Costs	17,742	14,548
Accrued Professional Fees	1,146	399
Other Accrued Expenses	2,637	3,768
Accrued Expenses	$ 28,657	$ 24,316