Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Subscription revenue	$ 36,091	$ 26,372	$ 28,610
Other revenue	3,821	3,947	5,884
Total revenue	39,912	30,319	34,494
Operating expenses:
Cost of subscription revenue	8,072	6,820	7,107
Cost of other revenue	2,604	2,579	3,932
Total cost of revenue, exclusive of depreciation and amortization shown below:	10,676	9,399	11,039
Research and development	13,891	12,545	11,112
Sales and marketing	13,754	9,102	10,648
General and administrative	11,705	9,140	8,782
Severance and related costs			154
Depreciation and amortization	4,450	3,022	3,450
Amortization of intangibles	492	106	66
Total operating expenses	54,968	43,314	45,251
Operating loss	(15,056)	(12,995)	(10,757)
Interest and other expense, net	(590)	(1,090)	(534)
Change in fair value of warrant liability	3	(124)	(125)
Loss before income taxes	(15,643)	(14,209)	(11,416)
Income tax (provision) benefit	(38)	(23)	244
Net loss	(15,681)	(14,232)	(11,172)
Dividends related to Series B convertible preferred stock	(588)	(589)	(589)
Net loss available to common stockholders	$ (16,269)	$ (14,821)	$ (11,761)
Per share of common stock:
Basic net loss available to common stockholders	$ (0.70)	$ (0.74)	$ (0.70)
Diluted net loss available to common stockholders	$ (0.70)	$ (0.74)	$ (0.70)
Shares used to calculate basic net loss per share	23,264	19,923	16,722
Shares used to calculate diluted net loss per share	23,264	19,923	16,722
Total Cost of Revenue [Member]
Stock-based compensation is included in individual line items above:
Stock-based compensation	$ 255	$ 181	$ 267
Research and Development [Member]
Stock-based compensation is included in individual line items above:
Stock-based compensation	1,075	1,326	1,821
Sales and Marketing [Member]
Stock-based compensation is included in individual line items above:
Stock-based compensation	1,330	696	1,615
General and Administrative [Member]
Stock-based compensation is included in individual line items above:
Stock-based compensation	$ 2,742	$ 1,975	1,872
Severance and Related Costs [Member]
Stock-based compensation is included in individual line items above:
Stock-based compensation			$ 29