Collaboration and License Agreements - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands		9 Months Ended
	Dec. 26, 2020	Dec. 31, 2022	Mar. 31, 2022
Cost Cash Advance from Collaboration Partner
Beginning balance		$ 33,818
Additions	$ 146,400	0
Ending balance		0
Deferred revenue, current		117,231	$ 100,564
Deferred revenue, non-current		350,014	375,706
Cost share advance from collaboration partner, current		0	33,818
Pfizer
Cost Cash Advance from Collaboration Partner
Additions	$ 150,000	100,000
Deductions		(34,386)
Ending balance		0
Collaboration expense to Pfizer
Deferred Revenue
Beginning balance		476,270
Additions		100,000
Imputed Interest		0
Deductions		(109,025)
Ending balance		467,245
Cost Cash Advance from Collaboration Partner
Deferred revenue, current		117,200	100,600
Deferred revenue, non-current		$ 350,000	$ 375,700