Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
License revenue	$ 38	$ 38
Research and development:
Noncash compensation	1,979	1,489
Other research and development	34,043	30,896
Total research and development	36,022	32,385
General and administrative:
Noncash compensation	9,089	393
Other general and administrative	5,172	1,949
Total general and administrative	14,261	2,342
Total costs and expenses	50,283	34,727
Operating loss	(50,245)	(34,689)
Other (income) expense:
Interest expense	1,201	774
Other income	(330)	(307)
Total other expense, net	871	467
Net loss	$ (51,116)	$ (35,156)
Basic and diluted net loss per common share (in dollars per share)	$ (0.48)	$ (0.43)
Weighted average shares used in computing basic and diluted net loss per common share (in shares)	105,461,892	81,174,301