Consolidated Statement of Operations - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Subscription and support	$ 17,062	$ 17,029	$ 16,220	$ 15,241	$ 14,719	$ 14,129	$ 14,023	$ 14,322	$ 65,552	$ 57,193	$ 48,625
Perpetual license	542	332	458	318	608	540	846	811	1,650	2,805	2,787
Total product revenue	17,604	17,361	16,678	15,559	15,327	14,669	14,869	15,133	67,202	59,998	51,412
Professional services	1,770	1,880	1,892	2,023	2,273	2,436	2,809	2,395	7,565	9,913	13,162
Total revenue	19,374	19,241	18,570	17,582	17,600	17,105	17,678	17,528	74,767	69,911	64,574
Cost of revenue:
Subscription and support	6,127	5,747	5,634	5,226	5,242	4,771	4,841	4,732	22,734	19,586	14,042
Professional services	1,056	1,045	1,106	1,624	1,768	1,677	1,732	1,908	4,831	7,085	9,079
Total cost of revenue	7,183	6,792	6,740	6,850	7,010	6,448	6,573	6,640	27,565	26,671	23,121
Gross profit	12,191	12,449	11,830	10,732	10,590	10,657	11,105	10,888	47,202	43,240	41,453
Operating expenses:
Sales and marketing	3,041	3,097	2,953	3,069	3,058	2,929	3,446	3,532	12,160	12,965	14,670
Research and development	3,218	3,737	4,054	3,910	3,848	3,852	4,152	3,926	14,919	15,778	26,165
Refundable Canadian tax credits	(173)	(115)	(116)	(109)	(112)	(115)	(122)	(121)	(513)	(470)	(1,094)
General and administrative	4,946	4,670	4,547	4,123	3,874	4,494	4,714	5,119	18,286	18,201	13,561
Depreciation and amortization	1,021	1,322	1,476	1,472	1,327	1,130	1,063	1,014	5,291	4,534	4,310
Acquisition-related expenses	728	1,047	1,380	2,428	1,374	176	360	545	5,583	2,455	2,186
Total operating expenses	12,781	13,758	14,294	14,893	13,369	12,466	13,613	14,015	55,726	53,463	59,798
Loss from operations	(590)	(1,309)	(2,464)	(4,161)	(2,779)	(1,809)	(2,508)	(3,127)	(8,524)	(10,223)	(18,345)
Other expense:
Interest expense, net	(849)	(709)	(662)	(561)	(473)	(462)	(576)	(347)	(2,781)	(1,858)	(1,951)
Other income (expense), net	427	(64)	(293)	(748)	(157)	137	(12)	(512)	(678)	(544)	101
Total other expense	(422)	(773)	(955)	(1,309)	(630)	(325)	(588)	(859)	(3,459)	(2,402)	(1,850)
Loss before provision for income taxes	(1,012)	(2,082)	(3,419)	(5,470)	(3,409)	(2,134)	(3,096)	(3,986)	(11,983)	(12,625)	(20,195)
Provision for income taxes	(961)	(308)	(158)	(103)	(854)	(190)	(238)	243	(1,530)	(1,039)	78
Net loss	$ (1,973)	$ (2,390)	$ (3,577)	$ (5,573)	$ (4,263)	$ (2,324)	$ (3,334)	$ (3,743)	(13,513)	(13,664)	(20,117)
Preferred stock dividends and accretion									0	0	(1,524)
Net loss attributable to common shareholders									$ (13,513)	$ (13,664)	$ (21,641)
Net loss per common share:
Net loss per common share, basic and diluted (in USD per share)	$ (0.12)	$ (0.14)	$ (0.22)	$ (0.36)	$ (0.28)	$ (0.16)	$ (0.22)	$ (0.25)	$ (0.82)	$ (0.91)	$ (4.43)
Weighted-average common shares outstanding, basic and diluted (in shares)									16,472,799	14,939,601	4,889,901