Consolidated Statements of Operations and Comprehensive Loss - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenues	$ 157,559	$ 2,937,991	$ 1,132,698	$ 5,872,321
Operating expenses:
Research and development	29,205,739	17,041,975	54,356,051	40,823,756
General and administrative	4,155,928	4,220,238	11,636,001	9,097,511
Impairment loss on construction-in-progress			8,070,000
Total operating expenses	33,361,667	21,262,213	74,062,052	49,921,267
Loss from operations	(33,204,108)	(18,324,222)	(72,929,354)	(44,048,946)
Other income (expense):
Interest expense	(32,866)	(2,275)	(66,763)	(7,468)
Interest income	12,485	45,127	87,847	278,154
Other (expense) income, net	(286,199)	29,218	(293,233)	48,882
Total other (expense) income, net	(306,580)	72,070	(272,149)	319,568
Net loss before income tax benefit	(33,510,688)	(18,252,152)	(73,201,503)	(43,729,378)
Income tax benefit	0	482,017	0	5,306,678
Net loss	(33,510,688)	(17,770,135)	(73,201,503)	(38,422,700)
Other comprehensive (loss) income - unrealized (loss) gain on short-term investments	(1,923)	(10,569)	4,354	(22,116)
Comprehensive loss	$ (33,512,611)	$ (17,780,704)	$ (73,197,149)	$ (38,444,816)
Net loss per share, basic	$ (0.81)	$ (0.54)	$ (1.79)	$ (1.74)
Net loss per share, diluted	$ (0.81)	$ (0.54)	$ (1.79)	$ (1.74)
Weighted-average common shares outstanding, basic and diluted	41,370,768	33,056,971	40,843,905	22,058,424