SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Prepaid and other current assets	$ 13,856		$ 13,856		$ 13,784	$ 11,881
Deferred income tax assets	73,163		73,163		19,626	20,156
Accumulated deficit	(632,910)		(632,910)		$ (706,981)	(708,354)
Income Statement Related Disclosures [Abstract]
Revenue	184,101	$ 152,773	365,136	$ 285,288
Income tax benefit	29,721	104	53,182	1,183
Net income from continuing operations	44,849	$ 8,007	80,706	$ 15,805
Balances without adoption of ASC Topic 606
Balance Sheet Related Disclosures [Abstract]
Prepaid and other current assets	11,061		11,061			11,881
Deferred income tax assets	73,693		73,693			20,156
Accumulated deficit	(635,175)		(635,175)			(708,354)
Income Statement Related Disclosures [Abstract]
Revenue	183,400		364,244
Income tax benefit	29,900		53,413
Net income from continuing operations	44,327		80,045
Adjustments due to ASC Topic 606 | Accounting Standards Update 2014-09
Balance Sheet Related Disclosures [Abstract]
Prepaid and other current assets	2,795		2,795			1,903
Deferred income tax assets	(530)		(530)			(530)
Accumulated deficit	2,265		2,265			$ 1,373
Income Statement Related Disclosures [Abstract]
Revenue	701		892
Income tax benefit	(179)		(231)
Net income from continuing operations	$ 522		$ 661