Collaboration and License Agreements - Contract Liabilities (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2020 USD ($)
Deferred revenue, current
Beginning balance	$ 40,000
Additions	93,897
Imputed Interest	0
Deductions	(33,333)
Ending balance	100,564
Cost share advance from collaboration partner, current
Beginning balance	0
Additions	100,000
Imputed Interest	0
Deductions	(7,585)
Ending balance	92,415
Deferred revenue, non-current
Beginning balance	0
Additions	419,723
Imputed Interest	0
Deductions	(1,379)
Ending balance	418,344
Cost share advance from collaboration partner, non-current
Beginning balance	0
Additions	46,384
Imputed Interest	40
Deductions	0
Ending balance	$ 46,424