NET PRODUCT REVENUES BY GEOGRAPHIC REGION AND BY SIGNIFICANT CUSTOMERS - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Entity Wide Revenue Major Customer [Line Items]
Total Net Product Revenues	$ 27,470	$ 20,453
Accredo Health Services [Member]
Entity Wide Revenue Major Customer [Line Items]
Total Net Product Revenues	$ 25,300	$ 19,300
Accredo Health Services [Member] | Sales [Member] | Customer Concentration Risk
Entity Wide Revenue Major Customer [Line Items]
Percentage of sales revenue	92.00%	94.20%