SELECTED QUARTERLY INFORMATION - UNAUDITED (Selected Quarterly 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
Selected Quarterly Financial Information [Abstract]
Total revenue, net	$ 241,160	$ 226,367	$ 212,673	$ 202,534	$ 219,074	$ 197,523	$ 197,043	$ 183,077	$ 882,734	$ 796,717	$ 696,832
Gross margin	151,159	140,298	137,422	127,313	134,050	123,627	123,538	112,556	556,192	493,771
Net (loss) income	$ 14,980	$ (31,881)	$ 12,020	$ 11,732	$ 20,405	$ 8,990	$ 4,282	$ 2,618	$ 6,851	$ 36,295	$ 22,027
Income from continuing operations	$ 0.41	$ (0.90)	$ 0.36	$ 0.36	$ 0.63	$ 0.28	$ 0.13	$ 0.08	$ 0.20	$ 1.12	$ 0.78
Income from continuing operations	$ 0.39	$ (0.90)	$ 0.35	$ 0.35	$ 0.62	$ 0.27	$ 0.13	$ 0.08	$ 0.19	$ 1.10	$ 0.76
Net (loss) income	$ 14,980	$ (31,881)	$ 4,998	$ 8,384	$ 17,166	$ 9,807	$ 4,825	$ 2,206	$ (3,519)	$ 34,004	$ (21,067)
Earnings Per Share, Basic (USD per share)	$ 0.41	$ (0.90)	$ 0.15	$ 0.26	$ 0.53	$ 0.30	$ 0.15	$ 0.07	$ (0.10)	$ 1.05	$ (0.74)
Earnings Per Share, Diluted (USD per share)	$ 0.39	$ (0.90)	$ 0.15	$ 0.25	$ 0.52	$ 0.30	$ 0.15	$ 0.07	$ (0.10)	$ 1.03	$ (0.74)