SEGMENT AND GEOGRAPHIC INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SEGMENT AND GEOGRAPHIC INFORMATION
Net product sales:	$ 125,179	$ 182,173	$ 104,897	$ 103,425	$ 124,279	$ 185,473	$ 104,259	$ 103,362	$ 515,674	$ 517,373	$ 536,692
Long-lived assets:	178,972				180,905				178,972	180,905	184,586
United States
SEGMENT AND GEOGRAPHIC INFORMATION
Net product sales:									472,222	475,055	492,450
Long-lived assets:	145,210				147,296				145,210	147,296	149,144
Canada
SEGMENT AND GEOGRAPHIC INFORMATION
Long-lived assets:	30,823				29,806				30,823	29,806	31,408
Canada, Mexico, and Other
SEGMENT AND GEOGRAPHIC INFORMATION
Net product sales:									43,452	42,318	44,242
Mexico and Other
SEGMENT AND GEOGRAPHIC INFORMATION
Long-lived assets:	$ 2,939				$ 3,803				$ 2,939	$ 3,803	$ 4,034