RESTRUCTURING COSTS AND ACCRUALS (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$ (932)	$ 4,059	$ 1,927	$ 4,991
Other Restructuring Costs	1,200	2,004	1,248	2,055
Restructuring accrual [Roll Forward]
New restructuring charges - operating expenses	268	6,063	3,175	7,046
Accretion			96
Cash payments			(3,489)
Foreign exchange impact on ending balance			4
Facilities-related accruals - current	2,568		2,568
Facilities-related accruals - non-current	447		447		$ 731
Restructuring Charges	268	6,063	3,175	7,046
Employee Severance [Member]
Restructuring accrual [Roll Forward]
Accrual balance at beginning of year			1,998
New restructuring charges - operating expenses	687	1,686	855	2,362
Accretion			0
Cash payments			(1,766)
Foreign exchange impact on ending balance			3
Accrual balance at end of period	1,090		1,090
Facilities-related accruals - current	1,090		1,090
Facilities-related accruals - non-current	0		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	3,015		3,015
Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Accrual balance at beginning of year			2,479
New restructuring charges - operating expenses	(1,619)	2,373	1,072	2,629
Revisions of estimated liabilities			1,500
Accretion			96
Cash payments			(1,723)
Foreign exchange impact on ending balance			1
Accrual balance at end of period	1,925		1,925
Facilities-related accruals - current	1,478		1,478
Facilities-related accruals - non-current	447		447
2016 Plan [Member]
Restructuring accrual [Roll Forward]
Restructuring Charges	300	$ 6,100	3,200	$ 7,000
Restructuring and Related Cost, Number of Positions Eliminated				58
2016 Plan [Member] | Employee Severance [Member]
Restructuring accrual [Roll Forward]
Restructuring Charges			800	$ 2,500
2016 Plan [Member] | Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Restructuring Charges				$ 4,500
Accrued Expenses and Other Current Liabilities [Member] | Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Facilities-related accruals - current	1,500		1,500
Other Noncurrent Liabilities [Member] | Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Facilities-related accruals - non-current	400		400
Property, Plant and Equipment [Member] | Facilities-Related [Member]
Restructuring accrual [Roll Forward]
Facilities-related accruals - non-current	$ 900		$ 900