SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition and Inventory (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Revenue recognized on an accrual basis	$ 72,574	$ 24,510	$ 174,074	$ 57,592
Revenue recognized when cash is received		3,605	4,509	6,543
Total	72,574	$ 28,115	178,583	$ 64,135
Inventory
Raw materials	7,033		7,033		$ 2,408
Semi-finished and finished goods	11,031		11,031		4,425
Total inventory	$ 18,064		$ 18,064		$ 6,833