Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 17,419	$ 15,680
General and administrative	5,842	5,124
Total operating expenses	23,261	20,804
Loss from operations	(23,261)	(20,804)
Other (expense) income:
Interest (expense) income, net	(181)	505
Other income	466	0
Other income, net	285	505
Loss before income taxes	(22,976)	(20,299)
Income tax expense	(65)	0
Net loss	$ (23,041)	$ (20,299)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.71)	$ (0.64)
Weighted-average number of common shares outstanding, basic and diluted (in shares)	32,250,050	31,925,072
Comprehensive loss:
Net loss	$ (23,041)	$ (20,299)
Other comprehensive loss:
Unrealized gain (loss) on investments, net of tax of $0	0	16
Comprehensive loss	$ (23,041)	$ (20,283)