Basis of Presentation and Summary of Significant Accounting Policies - Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Potentially dilutive securities have been excluded from the computation of diluted weighted average shares of common stock outstanding
Securities have been excluded from the computation of diluted weighted average shares of common stock outstanding	2,732,059	8,200,052
Stock options
Potentially dilutive securities have been excluded from the computation of diluted weighted average shares of common stock outstanding
Securities have been excluded from the computation of diluted weighted average shares of common stock outstanding	2,588,235	1,267,099
Convertible preferred stock
Potentially dilutive securities have been excluded from the computation of diluted weighted average shares of common stock outstanding
Securities have been excluded from the computation of diluted weighted average shares of common stock outstanding		6,759,109
Common stock warrants
Potentially dilutive securities have been excluded from the computation of diluted weighted average shares of common stock outstanding
Securities have been excluded from the computation of diluted weighted average shares of common stock outstanding	17,125
Preferred stock warrants
Potentially dilutive securities have been excluded from the computation of diluted weighted average shares of common stock outstanding
Securities have been excluded from the computation of diluted weighted average shares of common stock outstanding		17,125
BSA and BSPCE warrants
Potentially dilutive securities have been excluded from the computation of diluted weighted average shares of common stock outstanding
Securities have been excluded from the computation of diluted weighted average shares of common stock outstanding	126,699	156,719