Net Loss Per Share - Weighted Average Number of Common Shares Outstanding (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Loss from continuing operations	$ (2,629)	$ (1,909)	$ (8,053)	$ (6,157)
Loss from discontinued operations	(68)	(3,324)	(159)	(5,693)
Net loss	$ (2,697)	$ (5,233)	$ (8,212)	$ (11,850)
Denominator:
Weighted average common shares outstanding	11,102	8,526	10,102	8,520
Weighted average unvested common shares subject to repurchase	(55)	(38)	(69)	(43)
Weighted average common shares outstanding—basic	11,047	8,488	10,033	8,477
Effect of dilutive securities:
Effect of dilutive securities: conversion of preferred stock	0	0	0	0
Effect of dilutive securities: options	0	0	0	0
Effect of dilutive securities: warrants	0	0	0	0
Weighted average common shares outstanding—diluted	11,047	8,488	10,033	8,477
Net loss per share, basic and diluted:
Continuing operations, net loss per share, basic and diluted (in dollars per share)	$ (0.24)	$ (0.22)	$ (0.80)	$ (0.73)
Discontinued operations, net loss per share, basic and diluted	(0.01)	(0.39)	(0.02)	(0.67)
Net loss per basic and diluted share (in dollars per share)	$ (0.24)	$ (0.62)	$ (0.82)	$ (1.40)