CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
License revenue	$ 4,310	$ 0
Operating expenses:
Research and development	6,078	8,867
General and administrative	5,293	3,448
Change in fair value of contingent consideration	48,160	(53,700)
Total operating expenses	59,531	(41,385)
(Loss) Income from operations	(55,221)	41,385
Other (expense) income, net:
Other (expense) income, net	(3)	179
Net (Loss) Income and Comprehensive (Loss) Income Before Taxes	(55,224)	41,564
Provision for income taxes	(288)	0
Net (Loss) Income and Comprehensive (Loss) Income After Taxes	(55,512)	41,564
Net (loss) income attributable to common stockholders - basic	(55,512)	34,407
Net (loss) income attributable to common stockholders - diluted	$ (55,512)	$ 34,408
Earnings Per Share [Abstract]
Net (loss) per common share - basic (in dollars per share)	$ (0.35)	$ 0.31
Weighted-average common shares outstanding - basic (in shares)	157,033	109,808
Net income (loss) per share applicable to common stockholders - diluted (in dollars per share)	$ (0.35)	$ 0.31
Weighted-average common shares outstanding for diluted (in shares)	157,033	109,823