Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Consolidated Statements of Operations [Abstract]
Revenue	$ 0	$ 0
Operating expenses:
Research and development	28,542	16,957
General and administrative	10,680	7,163
Total operating expenses	39,222	24,120
Loss from operations	(39,222)	(24,120)
Research and development incentives	500	0
Interest expense	(1,729)	(1,573)
Interest and other income net	911	967
(Amortization of premium) accretion of discount on investments - net	(639)	62
Net loss	$ (40,179)	$ (24,664)
Net loss per share attributable to common stockholders - basic (in dollars per share)	$ (0.65)	$ (0.45)
Net loss per share attributable to common stockholders - diluted (in dollars per share)	$ (0.65)	$ (0.45)
Weighted-average common shares outstanding - basic (in shares)	61,574,405	54,883,120
Weighted-average common shares outstanding - diluted (in shares)	61,574,405	54,883,120