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NET REVENUES FROM COLLABORATIONS - Additional Information (Detail) $ in Thousands			1 Months Ended		3 Months Ended		12 Months Ended
	Mar. 31, 2025 USD ($)	Jul. 21, 2023 USD ($) performance_obligation	Mar. 31, 2025 USD ($)	Jun. 30, 2024 USD ($) performance_obligation	Mar. 31, 2025 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2019 USD ($) target	Dec. 31, 2024 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contract with customer liability revenue recognized					$ 28,100	$ 20,400
Research and development					265,122	260,995
Total revenues					594,189	494,333
Deferred revenue	$ 28,160		$ 28,160		28,160			$ 55,481
Net revenues from collaborations
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenues					$ 99,185	118,548
Vir Biotechnology, Inc. \| Net revenues from collaborations
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenues			30,000
Roche Collaboration and License Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development costs, percentage responsible		40.00%
Profit and loss sharing percentage		50.00%
Number of performance obligations \| performance_obligation		3
Roche Collaboration and License Agreement \| Roche
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development costs, percentage responsible		60.00%
Profit and loss sharing percentage		50.00%
Contingent termination fee		$ 50,000
Actual reimbursement of transactional price (as percent)					60.00%
Transaction Price Allocated	1,314,533
Unsatisfied performance obligations	854,000
Research and development					$ 29,700	18,100
Total revenues					15,840	72,151
Global Strategic Collaboration \| Regeneron Pharmaceuticals
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of performance obligations \| performance_obligation				2
Research and development					18,900	18,700
Upfront payment				$ 10,000
Maximum royalties and commercial milestone payments upon potential product sale				325,000
Discovery period of programs development							7 years
Extended additional discovery period of programs development							5 years
Research term extension fee							$ 300,000
Maximum additional milestone payments to be receive upon achievement of certain criteria							$ 100,000
Number of targeted programs \| target							6
Maximum percentage of royalty payments							20.00%
Contract with customer, liability	59,800		59,800		59,800
Global Strategic Collaboration \| Regeneron Pharmaceuticals \| C5 Monotherapy Obligation
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Fixed consideration				$ 191,500
Global Strategic Collaboration \| Regeneron Pharmaceuticals \| C5 License Obligation
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenues					21,500	1,700
Global Strategic Collaboration \| Regeneron Pharmaceuticals \| Regeneron Technology Transfer Obligation
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenues					2,400
Global Strategic Collaboration \| Regeneron Pharmaceuticals \| Research Services Obligation
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Transaction Price Allocated	100,500		100,500		100,500
Total revenues					13,800	$ 14,700
Deferred revenue	$ 27,300		$ 27,300		$ 27,300			$ 41,200
Global Strategic Collaboration \| Regeneron Pharmaceuticals \| Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement milestone payments, per collaboration project							$ 150,000
Royalty rate							20.00%
Global Strategic Collaboration \| Regeneron Pharmaceuticals \| Funding At Program Initiation
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential proceeds from collaboration arrangement							$ 2,500
Global Strategic Collaboration \| Regeneron Pharmaceuticals \| Funding At Lead Candidate Identification
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential proceeds from collaboration arrangement							$ 2,500
Product Alliances \| 2013 The Medicines Company Collaboration \| Maximum \| Novartis AG
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty rate	20.00%		20.00%		20.00%
Product Alliances \| 2013 The Medicines Company Collaboration \| Minimum \| Novartis AG
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty rate	10.00%		10.00%		10.00%