PRODUCT AND GEOGRAPHIC INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ 116,306	$ 93,461	$ 98,701	$ 103,319	$ 112,684	$ 104,046	$ 98,615	$ 97,937	$ 411,788	$ 413,282	$ 419,003
Long-lived assets	25,693				31,014				25,693	31,014
United States [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									152,012	150,877	161,155
Long-lived assets	18,506				23,774				18,506	23,774
Other Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									32,783	27,494	27,031
Europe, Middle East and Africa [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									161,764	172,238	163,059
Asia-Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									65,229	62,673	67,758
Other Countries [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Long-lived assets	$ 7,187				$ 7,240				7,187	7,240
Video products and solutions net revenues [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									131,225	132,276	114,787
Audio products and solutions net revenues [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									76,220	72,831	94,674
Subscription Arrangement [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									45,181	35,888	20,118
Nonsoftware Service, Support and Maintenance Arrangement [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									130,443	139,205	159,533
611710 Educational Support Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									28,719	33,082	29,891
Product [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues									$ 207,445	$ 205,107	$ 209,461