REVENUE FROM CONTRACTS FROM CUSTOMERS Financial Statement Impact of 606 - Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 126,690	$ 122,394	$ 380,572	$ 314,708
Cost of revenue, excluding amortization	91,771	93,475	281,813	236,122
Operating income (loss)	3,743	534	8,098	(11,944)
Loss before income taxes	(2,672)	(4,049)	(20,348)	(23,921)
Income tax (benefit) expense, net	(686)	1,980	(3,569)	5,039
Net loss	$ (1,986)	$ (6,029)	$ (16,779)	$ (28,960)
Basic net loss per share (in dollars per share)	$ (0.04)	$ (0.12)	$ (0.34)	$ (0.60)
Diluted net loss per share (in dollars per share)	$ (0.04)	$ (0.12)	$ (0.34)	$ (0.60)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 127,889		$ 380,142
Cost of revenue, excluding amortization	91,761		281,836
Operating income (loss)	4,953		7,645
Loss before income taxes	(1,462)		(20,801)
Income tax (benefit) expense, net	(371)		(3,544)
Net loss	$ (1,091)		$ (17,257)
Basic net loss per share (in dollars per share)	$ (0.02)		$ (0.35)
Diluted net loss per share (in dollars per share)	$ (0.02)		$ (0.35)