CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
SALES
Product	$ 284,147	$ 238,841	$ 227,905
Service	57,679	52,943	45,490
Total sales	341,826	291,784	273,395
COST OF SALES
Product	114,994	97,630	94,103
Service	37,918	32,261	29,673
Total cost of sales (exclusive of depreciation and amortization, shown separately below)	152,912	129,891	123,776
GROSS PROFIT	188,914	161,893	149,619
OPERATING EXPENSES
Selling and marketing	80,157	71,689	64,446
General and administrative	36,479	30,600	29,065
Depreciation and amortization	7,428	7,038	6,976
Research and development	27,510	22,412	17,578
Total operating expenses	151,574	131,739	118,065
INCOME FROM OPERATIONS	37,340	30,154	31,554
OTHER (INCOME) EXPENSE
Interest income	(96)	(74)	(160)
Other (income) expense, net	(94)	1,357	744
Interest expense	8	9	28
INCOME BEFORE INCOME TAX EXPENSE	37,522	28,862	30,942
INCOME TAX EXPENSE	3,873	7,353	7,944
NET INCOME	$ 33,649	$ 21,509	$ 22,998
NET INCOME PER SHARE - BASIC	$ 1.95	$ 1.26	$ 1.36
NET INCOME PER SHARE - DILUTED	$ 1.93	$ 1.25	$ 1.34
Weighted average shares - Basic	17,247,727	17,087,104	16,910,830
Weighted average shares - Diluted	17,416,453	17,241,115	17,129,128