Summary of Significant Accounting Policies - Potentially dilutive securities (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares	4,612,799	3,931,587
Stock Option
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares	552,605	472,450
Warrants
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares	88,556	88,556
Series A
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares	911,336	911,336
Series B
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares	3,060,302	2,459,245