Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Sales and service revenue
Product sales	$ 42,794	$ 42,704	$ 125,180	$ 119,102
Service revenue	27,842	22,063	81,532	69,912
Net sales	70,636	64,767	206,712	189,014
Cost of sales and service revenue
Cost of product sales	32,757	31,316	89,331	85,822
Cost of service revenue	19,295	18,119	65,312	58,057
Cost of sales	52,052	49,435	154,643	143,879
Gross profit	18,584	15,332	52,069	45,135
Selling, general and administrative expenses	10,050	8,681	28,011	25,855
Income from operations	8,534	6,651	24,058	19,280
Other income (expense):
Interest expense	(270)	(255)	(764)	(510)
Other, net	174	(289)	281	(851)
Total other expense	(96)	(544)	(483)	(1,361)
Income before income taxes	8,438	6,107	23,575	17,919
Provision for income taxes	2,799	2,029	8,039	5,606
Net income	5,639	4,078	15,536	12,313
Other comprehensive income
Foreign currency translation adjustment	(16)	0	(16)	0
Total comprehensive income	$ 5,623	$ 4,078	$ 15,520	$ 12,313
Amounts per common share:
Net income per common share (in dollars per share)	$ 0.48	$ 0.35	$ 1.33	$ 1.07
Net income per common share assuming dilution (in dollars per share)	$ 0.48	$ 0.35	$ 1.31	$ 1.05
Weighted average common shares outstanding (in shares)	11,736,392	11,584,510	11,675,453	11,547,558
Weighted average dilutive common shares outstanding (in shares)	11,857,611	11,755,055	11,827,867	11,732,989