Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Service	$ 12,936	$ 12,667	$ 12,517
Subscription	5,519	5,808	6,377
License	6,758	3,318	3,295
Total revenue	25,213	21,793	22,189
Cost of revenue:
Service	5,792	5,673	5,488
Subscription	2,264	2,410	3,113
License	502	414	346
Total cost of revenue	8,558	8,497	8,947
Gross profit	16,655	13,296	13,242
Operating expenses:
Sales and marketing	16,636	11,888	9,275
Research, development and engineering	15,435	13,394	12,465
General and administrative	9,680	8,298	7,954
Intellectual property	1,469	1,636	1,525
Total operating expenses	43,220	35,216	31,219
Operating loss	(26,565)	(21,920)	(17,977)
Other income, net	588	258	109
Loss before income taxes	(25,977)	(21,662)	(17,868)
Benefit (provision) for income taxes	206	(10)	(66)
Net loss	$ (25,771)	$ (21,672)	$ (17,934)
Earnings (loss) per common share:
Loss per common share—basic	$ (2.44)	$ (2.36)	$ (2.19)
Loss per common share—diluted	$ (2.44)	$ (2.36)	$ (2.19)
Weighted average common shares outstanding—basic	10,571	9,188	8,198
Weighted average common shares outstanding—diluted	10,571	9,188	8,198