RESTRUCTURING COSTS AND ACCRUALS (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$ 2,858	$ 935
Other Restructuring Costs	49	48
Restructuring accrual [Roll Forward]
New restructuring charges - operating expenses	2,907	983
Accretion	55
Cash payments	(2,227)
Foreign exchange impact on ending balance	14
Facilities-related accruals - current	3,185
Facilities-related accruals - non-current	1,992		$ 731
Restructuring Charges	2,907	983
Employee Severance [Member]
Restructuring accrual [Roll Forward]
Accrual balance at beginning of year	1,998
New restructuring charges - operating expenses	168	676
Accretion	0
Cash payments	(1,184)
Foreign exchange impact on ending balance	14
Accrual balance at end of period	996
Facilities-related accruals - current	996
Facilities-related accruals - non-current	0
Employee Severance [Member] | Acquisition-Related [Member]
Restructuring accrual [Roll Forward]
Accrual balance at beginning of year	4,477
Accrual balance at end of period	5,177
Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Accrual balance at beginning of year	2,479
New restructuring charges - operating expenses	2,690	259
Revisions of estimated liabilities	2,700
Accretion	55
Cash payments	(1,043)
Foreign exchange impact on ending balance	0
Accrual balance at end of period	4,181
Facilities-related accruals - current	2,189
Facilities-related accruals - non-current	1,992
2016 Plan [Member]
Restructuring accrual [Roll Forward]
Revisions of estimated liabilities		500
Restructuring Charges		$ 1,300
Restructuring and Related Cost, Number of Positions Eliminated		44
2016 Plan [Member] | Employee Severance [Member]
Restructuring accrual [Roll Forward]
Restructuring Charges	200
2016 Plan [Member] | Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Restructuring Charges		$ 200
Accrued Expenses and Other Current Liabilities [Member] | Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Facilities-related accruals - current	2,200
Other Noncurrent Liabilities [Member] | Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Facilities-related accruals - non-current	$ 2,000