CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
SALES
Product	$ 256,010	$ 259,842	$ 284,147
Service	69,574	57,706	57,679
Total sales	325,584	317,548	341,826
COST OF SALES
Product	107,965	114,257	115,266
Service	39,659	36,055	38,050
Total cost of sales (exclusive of depreciation and amortization, shown separately below)	147,624	150,312	153,316
GROSS PROFIT	177,960	167,236	188,510
OPERATING EXPENSES
Selling and marketing	79,870	79,837	80,804
General and administrative	40,813	36,370	35,331
Depreciation and amortization	13,868	11,217	7,428
Research and development	30,125	26,690	27,607
Total operating expenses	164,676	154,114	151,170
INCOME FROM OPERATIONS	13,284	13,122	37,340
OTHER EXPENSE (INCOME)
Interest income	(212)	(111)	(96)
Other expense (income), net	822	371	(94)
Interest expense	48	56	8
INCOME BEFORE INCOME TAX EXPENSE (BENEFIT)	12,626	12,806	37,522
INCOME TAX EXPENSE (BENEFIT)	1,519	(7)	3,873
NET INCOME	$ 11,107	$ 12,813	$ 33,649
NET INCOME PER SHARE - BASIC (in dollars per share)	$ 0.67	$ 0.74	$ 1.95
NET INCOME PER SHARE - DILUTED (in dollars per share)	$ 0.67	$ 0.74	$ 1.93
Weighted average shares - Basic (in shares)	16,654,786	17,288,665	17,247,727
Weighted average shares - Diluted (in shares)	16,681,710	17,389,473	17,416,453