QUARTERLY RESULTS (UNAUDITED) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net revenues	$ 138,806	$ 137,436	$ 109,767	$ 119,586	$ 128,196	$ 142,429	$ 124,644	$ 134,982	$ 505,595	$ 530,251	$ 563,412
Cost of revenues	54,912	47,672	43,306	47,492	50,548	52,788	50,420	50,665
Cost of products									131,881	143,765	159,264
Cost of services									61,501	60,656	63,177
Amortization of intangible assets	1,950	1,950	163	0	0	0	0	50	4,063	50	1,468
Gross profit	81,944	87,814	66,298	72,094	77,648	89,641	74,224	84,267	308,150	325,780	339,503
Operating expenses:
Research and development	24,190	25,225	23,310	23,173	23,212	22,154	22,070	22,954	95,898	90,390	95,249
Marketing and selling	30,091	31,564	32,811	28,045	34,527	31,410	34,297	32,815	122,511	133,049	133,890
General and administrative	21,463	15,834	17,425	19,387	22,222	20,644	19,984	18,331	74,109	81,181	77,578
Amortization of intangible assets	786	786	408	374	375	373	398	480	2,354	1,626	2,648
Restructuring costs (recoveries), net	5,766	0	539	0	0	0	(165)	0	6,305	(165)	5,370
Total operating expenses	82,296	73,409	74,493	70,979	80,336	74,581	76,584	74,580	301,177	306,081	314,735
Operating (loss) income	(352)	14,405	(8,195)	1,115	(2,688)	15,060	(2,360)	9,687	6,973	19,699	24,768
Other (expense) income, net	(1,727)	(2,519)	(1,439)	(723)	(1,620)	(455)	(357)	(351)	(175)	(1,138)	343
(Loss) income before income taxes	(2,079)	11,886	(9,634)	392	(4,308)	14,605	(2,717)	9,336	565	16,916	24,092
Provision for (benefit from) income taxes	2,306	768	(5,550)	561	761	365	622	440	(1,915)	2,188	2,939
Net (loss) income	$ (4,385)	$ 11,118	$ (4,084)	$ (169)	$ (5,069)	$ 14,240	$ (3,339)	$ 8,896	$ 2,480	$ 14,728	$ 21,153
(Loss) income per common share - basic and diluted	$ (0.11)	$ 0.28	$ (0.10)	$ 0.00	$ (0.13)	$ 0.36	$ (0.09)	$ 0.23	$ 0.06	$ 0.38	$ 0.54
Weighted-average common shares outstanding - basic	39,439	39,231	39,635	39,387	39,234	39,133	39,119	39,099	39,423	39,147	39,044
Weighted-average common shares outstanding - diluted	39,439	39,750	39,635	39,387	39,234	39,201	39,119	39,122	40,380	39,267	39,070