REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 38,432	$ 33,620
Bile acid products
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	18,508	15,736
Thiola
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 19,924	$ 17,884
Geographic Concentration Risk | Revenue from Contract with Customer | United States
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	95.00%