Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Sales:
Product	$ 73,075	$ 76,213	$ 81,143
Service	103,047	108,421	91,448
Net sales	176,122	184,634	172,591
Costs and expenses:
Costs of product sales	46,334	47,404	48,843
Costs of service sales	52,966	54,816	50,301
Research and development	16,030	14,039	14,101
Sales, marketing and support	33,942	35,714	32,976
General and administrative	28,172	29,453	24,448
Total costs and expenses	177,444	181,426	170,669
(Loss) income from operations	(1,322)	3,208	1,922
Interest income	513	546	738
Interest expense	1,436	1,460	1,296
Other income (expense), net	275	372	(39)
(Loss) income before income tax expense	(1,970)	2,666	1,325
Income tax expense	5,547	413	1,284
Net (loss) income	$ (7,517)	$ 2,253	$ 41
Per share information:
Net income per share, basic (in dollars per share)	$ (0.47)	$ 0.14	$ 0.00
Net income per share, diluted (in dollars per share)	$ (0.47)	$ 0.14	$ 0.00
Number of shares used in per share calculation:
Basic (in shares)	15,834	15,625	15,420
Diluted (in shares)	15,834	15,834	15,605