STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Collaboration revenue			$ 146
Operating expenses:
Research and development	$ 52,696	$ 38,331	34,134
General and administrative	27,665	19,527	19,918
Total operating expenses	80,361	57,858	54,052
Loss from operations	(80,361)	(57,858)	(53,906)
Other income, net	385	813	631
Non-cash inducement warrant expense		(60,751)
Change in fair value of derivative liabilities	0	0	158
Net loss	(79,976)	(117,796)	(53,117)
Preferred stock dividends			(16,998)
Settlement of a related party relationship			207,361
Net income (loss) applicable to common stockholders	$ (79,976)	$ (117,796)	$ 137,246
Net income (loss) per share - basic	$ (0.38)	$ (0.70)	$ 0.96
Net income (loss) per share - diluted	$ (0.38)	$ (0.70)	$ 0.96
Weighted average common shares outstanding used to compute basic net income (loss) per share	209,636,456	167,952,114	143,508,674
Weighted average common shares outstanding used to compute diluted net income (loss) per share	209,636,456	167,952,114	143,710,160