Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Collaboration revenue	$ 1,032	$ 1,069	$ 2,281	$ 1,069
Operating expenses:
Research and development	34,373	27,096	67,613	51,448
Selling, general and administrative	24,431	15,459	45,749	26,377
Acquired in-process research and development expense	1,500	0	3,000	0
Change in fair value of contingent consideration	12,200	(700)	4,300	2,300
Total operating expenses	72,504	41,855	120,662	80,125
Loss from operations	(71,472)	(40,786)	(118,381)	(79,056)
Other (expense) income, net	(157)	40	19,864	(48)
Interest income	880	2,983	1,968	6,139
Loss before income taxes	(70,749)	(37,763)	(96,549)	(72,965)
Income tax benefit	(17,425)	0	(17,425)	0
Net loss	$ (53,324)	$ (37,763)	$ (79,124)	$ (72,965)
Net loss per share, basic and diluted
Net loss per share, basic and diluted (in dollars per share)	$ (0.96)	$ (0.89)	$ (1.53)	$ (1.72)
Weighted average number of shares used in the calculation of basic and diluted net loss per common share (in shares)	55,355	42,458	51,770	42,348