UNAUDITED QUARTERLY FINANCIAL INFORMATION (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 95,573	$ 86,530	$ 88,966	$ 88,717	$ 93,530	$ 87,086	$ 85,432	$ 82,971	$ 359,786	$ 349,019	$ 330,399
Total cost of goods sold	33,762	31,017	31,887	33,879	34,588	35,566	36,588	36,416
Net income (loss)	$ 4,057	$ (5,336)	$ 7,006	$ 4,386	$ 5,167	$ 2,384	$ (911)	$ (10,474)	$ 10,113	$ (3,834)	$ (16,327)
Basic net (loss) income per common share (in dollars per share)	$ 0.05	$ (0.07)	$ 0.09	$ 0.06	$ 0.07	$ 0.03	$ (0.01)	$ (0.14)
Diluted net (loss) income per common share (in dollars per share)	$ 0.05	$ (0.07)	$ 0.08	$ 0.06	$ 0.05	$ 0.03	$ (0.01)	$ (0.14)