Net Loss per Common Share - Computation of Basic and Diluted Net Loss per Common Share (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic and diluted net loss per common share:
Net loss	$ (34,882,677)	$ (32,284,209)	$ (29,259,970)	$ (22,924,815)	$ (18,326,992)	$ (32,484,146)	$ (96,426,856)	$ (73,735,953)
Weighted average common shares outstanding, basic and diluted	37,680,966			37,311,726			37,569,416	37,158,513
Net loss per common share, basic and diluted	$ (0.93)			$ (0.61)			$ (2.57)	$ (1.98)