Loss Per Share (Details) - shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Loss Per Share
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding	2,295,891	14,266,146
Convertible preferred stock
Loss Per Share
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding		12,111,706
Convertible preferred stock warrants
Loss Per Share
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding		65,434
Convertible common stock warrants
Loss Per Share
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding	100,558
Common stock options
Loss Per Share
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding	2,195,333	2,089,006