SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Prepaid and other current assets	$ 13,551		$ 13,784	$ 11,881
Deferred income tax assets	45,406		19,626	20,156
Accumulated deficit	(675,457)		$ (706,981)	(708,354)
Income Statement Related Disclosures [Abstract]
Revenue	181,035	$ 132,515
Income tax benefit	23,461	1,079
Net income from continuing operations	35,857	$ 7,798
Balances without adoption of ASC Topic 606
Balance Sheet Related Disclosures [Abstract]
Prepaid and other current assets	11,456			11,881
Deferred income tax assets	45,936			20,156
Accumulated deficit	(677,022)			(708,354)
Income Statement Related Disclosures [Abstract]
Revenue	180,844
Income tax benefit	23,513
Net income from continuing operations	35,718
Adjustments due to ASC Topic 606 | Accounting Standards Update 2014-09
Balance Sheet Related Disclosures [Abstract]
Prepaid and other current assets	2,095			1,903
Deferred income tax assets	(530)			(530)
Accumulated deficit	1,565			$ 1,373
Income Statement Related Disclosures [Abstract]
Revenue	191
Income tax benefit	(52)
Net income from continuing operations	$ 139