PURCHASED INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Purchased intangible assets
Gross	$ 55,499	$ 57,731
Accumulated Amortization	(52,572)	(54,066)
Net	2,927	3,665
Core technology
Purchased intangible assets
Gross	16,881	17,899
Accumulated Amortization	(13,954)	(14,234)
Net	2,927	3,665
Customer relationships
Purchased intangible assets
Gross	36,516	37,638
Accumulated Amortization	(36,516)	(37,638)
Net	0	0
Trademarks / Trade names
Purchased intangible assets
Gross	2,102	2,194
Accumulated Amortization	(2,102)	(2,194)
Net	$ 0	$ 0