SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ 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
Selected Quarterly Financial Information [Abstract]
Revenue	$ 182,582	$ 198,692	$ 218,106	$ 217,810	$ 240,123	$ 224,542	$ 232,462	$ 238,462	$ 817,190	$ 935,589	$ 982,223
Gross profit	70,194	66,563	67,611	64,874	73,793	61,721	63,266	63,302	269,242	262,082	259,952
Loss from continuing operations, before income taxes	(7,202)	(12,998)	(28,432)	(18,801)	(4,064)	(11,012)	(8,770)	(10,311)	(67,433)	(34,157)	(326,351)
(Loss) income from discontinued operations, net of income taxes	(287)	66	(373)	(299)	(7,373)	107	169	504	(893)	(6,593)	4,691
Net loss	$ (1,962)	$ (12,992)	$ (29,523)	$ (19,719)	$ (12,858)	$ (11,327)	$ (8,750)	$ (9,830)	$ (64,196)	$ (42,765)	$ (300,128)
Loss from continuing operations, basic and diluted (in USD per share)	$ (0.03)	$ (0.12)	$ (0.26)	$ (0.18)	$ (0.06)	$ (0.11)	$ (0.14)	$ (0.17)	$ (0.59)	$ (0.48)	$ (4.58)
Income (loss) from discontinued operations, basic and diluted (in USD per share)	(0.01)	0.00	0.00	0.00	(0.07)	0.00	0.00	0.00	(0.01)	(0.07)	0.07
Net loss, basic and diluted (in USD per share)	$ (0.04)	$ (0.12)	$ (0.26)	$ (0.18)	$ (0.13)	$ (0.11)	$ (0.14)	$ (0.17)	$ (0.60)	$ (0.55)	$ (4.51)