CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
License revenue	$ 11,236	$ 0	$ 11,236	$ 0
Operating expenses:
Research and development	10,196	6,613	23,625	19,243
General and administrative	4,115	3,238	10,882	8,910
Change in fair value of contingent consideration	18,400	3,600	16,820	46,600
Total operating expenses	32,711	13,451	17,687	74,753
Loss from operations	(21,475)	(13,451)	(6,451)	(74,753)
Other income (expense), net:
Other income (expense), net	(1)	319	195	806
Net Loss and Comprehensive Loss Before Taxes	(21,476)	(13,132)	(6,256)	(73,947)
Provision for income taxes	(1,132)	0	(1,132)	0
Net Loss and Comprehensive Loss After Taxes	(22,608)	(13,132)	(7,388)	(73,947)
Deemed dividend on adjustment of exercise price on certain warrants	0		(147)	0
Net Loss and Comprehensive Loss Attributable to Common Shareholders	$ (22,608)	$ (13,132)	$ (7,535)	$ (73,947)
Earnings Per Share [Abstract]
Net loss per common share - basic and diluted (in dollars per share)	$ (0.19)	$ (0.13)	$ (0.07)	$ (0.85)
Weighted -average common shares outstanding - basic and diluted (in shares)	117,886	101,266	113,437	86,575