Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
License and milestone revenue	$ 33,333	$ 0
Operating expenses:
Research and development	44,186	51,117
General and administrative	22,828	14,152
Total operating expenses	67,014	65,269
Loss from operations	(33,681)	(65,269)
Interest expense	0	3,793
Interest expense (related party)	2,184	0
Interest income	(108)	(766)
Other income, net	(3,569)	(705)
Loss before income taxes	(32,188)	(67,591)
Income tax expense	672	313
Net loss	$ (32,860)	$ (67,904)
Net loss per common share — basic and diluted (in USD per share)	$ (0.37)	$ (0.89)
Weighted average common shares outstanding — basic and diluted (in shares)	89,300,210	76,468,347
Revenue, Product and Service [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember