Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Subscription revenue	$ 38,720	$ 36,091	$ 26,372
Other revenue	3,377	3,821	3,947
Total revenue	42,097	39,912	30,319
Operating expenses:
Cost of subscription revenue	10,365	8,072	6,820
Cost of other revenue	3,423	2,604	2,579
Total cost of revenue, exclusive of depreciation and amortization	13,788	10,676	9,399
Research and development	12,502	13,891	12,545
Sales and marketing	16,848	13,754	9,102
General and administrative	11,827	11,705	9,140
Depreciation and amortization	5,478	4,450	3,022
Amortization of intangibles	468	492	106
Total operating expenses	60,911	54,968	43,314
Operating loss	(18,814)	(15,056)	(12,995)
Non-operating income (expense):
Interest and other borrowing costs	(2,319)	(600)	(1,092)
Change in fair value of warrant liability	167	3	(124)
Other non-operating income	39	10	2
Total non-operating income (expense)	(2,113)	(587)	(1,214)
Loss before income taxes	(20,927)	(15,643)	(14,209)
Income tax provision	(50)	(38)	(23)
Net loss	(20,977)	(15,681)	(14,232)
Dividends related to 7% Series B convertible preferred stock	(586)	(588)	(589)
Net loss available to common stockholders	$ (21,563)	$ (16,269)	$ (14,821)
Per share of common stock:
Basic net loss available to common stock holders	$ (0.86)	$ (0.70)	$ (0.74)
Diluted net loss available to common stock holders	$ (0.86)	$ (0.70)	$ (0.74)
Shares used to calculate basic net loss per share	25,209	23,264	19,923
Shares used to calculate diluted net loss per share	25,209	23,264	19,923
Total Cost of Revenue [Member]
Stock-based compensation expense is included in individual line items above:
Stock-based compensation expense	$ 371	$ 255	$ 181
Research and Development [Member]
Stock-based compensation expense is included in individual line items above:
Stock-based compensation expense	1,134	1,075	1,326
Sales and Marketing [Member]
Stock-based compensation expense is included in individual line items above:
Stock-based compensation expense	1,697	1,330	696
General and Administrative [Member]
Stock-based compensation expense is included in individual line items above:
Stock-based compensation expense	$ 2,122	$ 2,742	$ 1,975