Grant Agreements (Details) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended
	Jan. 13, 2022 USD ($) $ / shares shares	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($) option	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reserve for remaining estimated manufacturing expenses				$ 94,658		$ 94,658		$ 104,220
Number of options to support the research and development | option			12
Other current assets				0		0		7,600
VIR Biomedical Advanced Research and Development Authority | Grant revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants				500	$ 2,900	5,600	$ 29,000
Human Immunodeficiency Virus ('HIV') Grant | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount. maximum				49,900		49,900
Vaccinal Antibody Grant | Grant revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants				1,600	3,800	3,800	10,500
Vaccinal Antibody Grant | Bill And Melinda Gates Foundation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock shares purchased (in shares) | shares	881,365
Common stock, shares purchased price (in USD per share) | $ / shares	$ 45.38
Common stock, shares purchased, aggregate purchase price	$ 40,000
Common stock, shares issued, fair market value	$ 28,500
Closing stock price (in USD per share) | $ / shares	$ 37.65
Premium received	$ 11,300
Deferred revenue				13,700		13,700		13,100
Reserve for remaining estimated manufacturing expenses				9,700		9,700		$ 9,200
BARDA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Base period funding			$ 55,000
New funding		$ 50,100			50,100		50,100
Potential future reimbursement				8,900		8,900
BARDA | development of VIR-7229 through a Phase 1 clinical trial
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
New funding		40,000			40,000		40,000
Collaborative arrangement, rights and obligations, decrease in funding				$ 42,100		$ 42,100
BARDA | New Monoclonal Antibody Discovery
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
New funding		10,100			$ 10,100		$ 10,100
BARDA | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Maximum grant amount to be received			$ 1,000,000
Additional funding		$ 11,200