CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SALES
Product	$ 277,922	$ 256,010	$ 259,842
Service	82,995	69,574	57,706
Total sales	360,917	325,584	317,548
COST OF SALES
Product	110,143	107,965	114,257
Service	46,137	39,659	36,055
Total cost of sales (exclusive of depreciation and amortization, shown separately below)	156,280	147,624	150,312
GROSS PROFIT	204,637	177,960	167,236
OPERATING EXPENSES
Selling and marketing	103,544	79,870	79,837
General and administrative	43,807	40,813	36,370
Depreciation and amortization	16,588	13,868	11,217
Research and development	35,376	30,125	26,690
Total operating expenses	199,315	164,676	154,114
INCOME FROM OPERATIONS	5,322	13,284	13,122
OTHER EXPENSE (INCOME)
Interest income	(319)	(212)	(111)
Other (income) expense, net	(190)	822	371
Interest expense	4	48	56
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)	5,827	12,626	12,806
INCOME TAX EXPENSE (BENEFIT)	20,343	1,519	(7)
NET (LOSS) INCOME	$ (14,516)	$ 11,107	$ 12,813
NET (LOSS) INCOME PER SHARE - BASIC (in dollars per share)	$ (0.87)	$ 0.67	$ 0.74
NET (LOSS) INCOME PER SHARE - DILUTED (in dollars per share)	$ (0.87)	$ 0.67	$ 0.74
Weighted average shares - Basic (in shares)	16,711,534	16,654,786	17,288,665
Weighted average shares - Diluted (in shares)	16,711,534	16,681,710	17,389,473