Condensed Consolidated Statements of Operations (Unaudited) - 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]
Net product sales	$ 1,520	$ 0	$ 1,520	$ 0
Collaboration revenue	1,340	630	3,621	1,699
Total revenues	2,860	630	5,141	1,699
Costs and expenses:
Cost of product sales (excluding amortization of intangible asset)	140	0	140	0
Research and development	34,425	28,372	102,038	79,820
Selling, general and administrative	24,583	15,762	70,332	42,139
Amortization of intangible asset	1,971	0	1,971	0
Acquired in-process research and development and acquisition-related costs	1,500	249,437	4,500	249,437
Change in fair value of contingent consideration	1,800	400	6,100	2,700
Total costs and expenses	64,419	293,971	185,081	374,096
Loss from operations	(61,559)	(293,341)	(179,940)	(372,397)
Other income, net	934	481	20,798	433
Interest income, net	536	2,382	2,504	8,521
Loss before income taxes	(60,089)	(290,478)	(156,638)	(363,443)
Income tax benefit	0	0	(17,425)	0
Net loss	$ (60,089)	$ (290,478)	$ (139,213)	$ (363,443)
Net loss per share, basic and diluted
Net loss per share, basic and diluted (in dollars per share)	$ (1.08)	$ (6.75)	$ (2.62)	$ (8.54)
Weighted average number of shares used in the calculation of basic and diluted net loss per common share (in shares)	55,548	43,029	53,039	42,577