ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Description of Business
Number of operating segments | segment	2
Effect of Adoption of ASC Topic 606
Deferred tax assets	$ 75,449		$ 68,394	$ 68,126
Accrued expenses and other current liabilities	64,695		67,710	66,683
Accumulated deficit	(383,149)		(360,531)	$ (359,772)
General and administrative expenses	25,636	$ 25,386
Non-service defined benefit plan expense	176	184
ASU 2017-07
Effect of Adoption of ASC Topic 606
General and administrative expenses	(200)	(200)
Non-service defined benefit plan expense	200	$ 200
Before adoption of ASC 606 | ASU 2014-09
Effect of Adoption of ASC Topic 606
Deferred tax assets	75,173
Accrued expenses and other current liabilities	63,638
Accumulated deficit	(382,368)
Adjustments | ASU 2014-09
Effect of Adoption of ASC Topic 606
Contract liability	1,000
Deferred tax assets	(276)		268
Accrued expenses and other current liabilities	(1,057)		1,027
Accumulated deficit	$ 781		$ (759)