Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
SALES
Product	$ 238,841	$ 227,905	$ 212,635
Service	52,943	45,490	41,529
Total Sales	291,784	273,395	254,164
COST OF SALES
Product	97,630	94,103	82,408
Service	32,261	29,673	28,067
Total Cost of Sales (exclusive of depreciation and amortization, shown separately below)	129,891	123,776	110,475
GROSS PROFIT	161,893	149,619	143,689
OPERATING EXPENSES:
Selling	71,689	64,446	62,117
General and administrative	30,600	29,065	26,806
Depreciation and amortization	7,038	6,976	6,712
Research and development	22,412	17,578	15,196
Total operating expenses	131,739	118,065	110,831
INCOME FROM OPERATIONS	30,154	31,554	32,858
OTHER (INCOME) EXPENSE
Interest income	(74)	(160)	(101)
Other expense, net	1,357	744	1,217
Interest expense	9	28	37
INCOME (LOSS) BEFORE INCOME TAX EXPENSE	28,862	30,942	31,705
INCOME TAX EXPENSE	7,353	7,944	8,328
NET INCOME	$ 21,509	$ 22,998	$ 23,377
NET INCOME PER SHARE - BASIC	$ 1.26	$ 1.36	$ 1.42
NET INCOME PER SHARE - DILUTED	$ 1.25	$ 1.34	$ 1.39
Weighted average shares - Basic	17,087,104	16,910,830	16,503,773
Weighted average shares - Diluted	17,241,115	17,129,128	16,868,471