Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Sales:
Product	$ 56,968	$ 73,075	$ 76,213
Service	103,120	103,047	108,421
Net sales	160,088	176,122	184,634
Costs and expenses:
Costs of product sales	37,474	46,334	47,404
Costs of service sales	52,692	52,966	54,816
Research and development	15,858	16,030	14,039
Sales, marketing and support	33,896	33,942	35,714
General and administrative	28,932	28,172	29,453
Total costs and expenses	168,852	177,444	181,426
(Loss) income from operations	(8,764)	(1,322)	3,208
Interest income	659	513	546
Interest expense	1,467	1,436	1,460
Other (expense) income, net	(366)	275	372
(Loss) income before income tax expense	(9,938)	(1,970)	2,666
Income tax expense	1,096	5,547	413
Net (loss) income	$ (11,034)	$ (7,517)	$ 2,253
Per share information:
Net income per share, basic (in dollars per share)	$ (0.67)	$ (0.47)	$ 0.14
Net income per share, diluted (in dollars per share)	$ (0.67)	$ (0.47)	$ 0.14
Number of shares used in per share calculation:
Basic (in shares)	16,419	15,834	15,625
Diluted (in shares)	16,419	15,834	15,834