DEFERRED REVENUE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes in deferred revenue [Roll Forward]
Deferred revenue at beginning of year	$ 19,404	$ 18,516
Deferred revenue at end of year	23,066	19,404
Less: current portion	15,540	7,628
Long-term deferred revenue at end of year	7,526	11,776
Deferred Extended Service Contracts [Member]
Changes in deferred revenue [Roll Forward]
Additions	705	502
Recognized as revenue	(661)	(753)
Deferred In-Service and Training [Member]
Changes in deferred revenue [Roll Forward]
Additions	20	23
Recognized as revenue	(20)	(28)
Deferred Service Arrangements [Member]
Changes in deferred revenue [Roll Forward]
Additions	43	55
Recognized as revenue	(45)	(47)
Deferred Commission Revenues [Member]
Changes in deferred revenue [Roll Forward]
Additions	14,779	13,120
Recognized as revenue	$ (11,159)	$ (11,984)