Net Loss per Share - Antidilutive securities excluded from EPS (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Securities excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from calculation of diluted net loss per share	6,241,321	5,539,621	6,241,321	3,847,500
Options to purchase common shares
Securities excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from calculation of diluted net loss per share	6,019,570	4,717,870	6,019,570	3,247,500
Warrants to purchase common shares
Securities excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from calculation of diluted net loss per share	221,751	821,751	221,751	600,000