CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Sales and service revenue
Product sales	$ 168,943		$ 161,435	$ 143,919
Service revenues	109,686		92,605	79,437
Net sales	278,629		254,040	223,356
Cost of sales and service revenue
Cost of product sales	121,247		117,368	106,891
Cost of service revenues	89,074		77,022	64,965
Cost of sales	210,321		194,390	171,856
Gross profit	68,308		59,650	51,500
Selling, general and administrative expenses	36,891		34,726	32,435
Acquisitions expense	5,362		0	0
Income from operations	26,055		24,924	19,065
Other income (expense):
Interest expense	(1,771)		(669)	(696)
Other, net	356		(730)	58
Total other expense	(1,415)		(1,399)	(638)
Income before income taxes	24,640		23,525	18,427
Provision for income taxes	8,153		7,136	5,496
Net income	16,487	[1]	16,389	12,931
Other comprehensive income (expense):
Change in foreign currency translation adjustment	(49)		0	0
Total comprehensive income	$ 16,438		$ 16,389	$ 12,931
Amounts per common share:
Net income per common share (in dollars per share)	$ 1.41		$ 1.42	$ 1.13
Net income per common share assuming dilution (in dollars per share)	$ 1.39		$ 1.40	$ 1.11
Weighted average common shares outstanding (in shares)	11,701,607		11,559,895	11,420,524
Weighted average dilutive common shares outstanding (in shares)	11,839,182		11,741,513	11,636,385

[1] The fourth quarter of 2012 includes $4,860 in acquisition fees related to Valent.