SIGNIFICANT ACCOUNTING POLICIES - Purchased Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Purchased intangible assets
Weighted average amortization period	12 years
Gross	$ 55,742	$ 57,342
Accumulated Amortization	(39,915)	(36,924)
Net	15,827	20,418
Expected future amortization of intangible assets
2017	3,878
2018	2,687
2019	1,533
2020	1,533
2021	1,174
Thereafter	5,022
Net	$ 15,827	20,418
Core technology [Member]
Purchased intangible assets
Weighted average amortization period	20 years
Gross	$ 17,751	18,524
Accumulated Amortization	(8,165)	(7,528)
Net	9,586	10,996
Expected future amortization of intangible assets
Net	$ 9,586	10,996
Customer relationships [Member]
Purchased intangible assets
Weighted average amortization period	9 years
Gross	$ 36,088	36,830
Accumulated Amortization	(29,965)	(27,701)
Net	6,123	9,129
Expected future amortization of intangible assets
Net	$ 6,123	9,129
Trademarks / Trade names [Member]
Purchased intangible assets
Weighted average amortization period	9 years
Gross	$ 1,903	1,988
Accumulated Amortization	(1,785)	(1,695)
Net	118	293
Expected future amortization of intangible assets
Net	$ 118	$ 293