REVENUE RECOGNITION - Total Gross Product (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Provision for product sales allowances and accruals:
Product sales, net	$ 89,707	$ 84,131	$ 78,109	$ 75,804	$ 88,122	$ 122,238	$ 146,254	$ 117,387	$ 327,751	$ 474,002	$ 495,769
Product sales, net
Disaggregation of Revenue [Line Items]
Gross product sales									955,693	974,330	920,061
Provision for product sales allowances and accruals:
Contractual adjustments									530,645	387,540	310,588
Governmental rebates									113,858	112,938	113,828
Total									644,503	500,478	424,416
Product sales, net									$ 311,190	$ 473,852	$ 495,645