Net Loss per Share - EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator
Net loss	$ (1,464)	$ (286)	$ (4,345)	$ (77)
Accretion of redeemable convertible preferred stock		(604)		(202)
Net loss attributable to common stockholders, basic	(1,464)	(890)	(4,345)	(279)
Net loss attributable to common stockholders, diluted	$ (1,464)	$ (890)	$ (4,345)	$ (279)
Denominator (basic and diluted):
Weighted average common shares outstanding basic and diluted (in shares)	16,506,585	4,860,758	16,373,413	4,765,977
Net loss per share attributable to common stock holders, basic and diluted (in dollars per share)	$ (0.09)	$ (0.18)	$ (0.27)	$ (0.06)