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Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended		12 Months Ended
	May 19, 2025	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Contingencies And Commitments [Line Items]
Research and development expense		$ 67,152		$ 69,894	$ 135,726	$ 142,378
Letters of credit secured by cash held in restricted depository account		377		3,514	377	3,514
Total liability associated with the contingent loss		18,300	$ 14,500		18,300
Restricted cash		7,629	7,629	$ 8,006	7,629	$ 8,006
Deferred Finance Costs, Share Lending Arrangement, Issuance Costs							$ 221,800	$ 221,800	$ 221,800
Contingent payments		0			0
Prepaid Expenses and Other Current Assets [Member]
Contingencies And Commitments [Line Items]
Letters of credit secured by cash held in restricted depository account		400	3,900		400
Sirius Therapeutics [Member]
Contingencies And Commitments [Line Items]
Research and development expense		3,400			5,000
Contingent payments		0			0
Future development regulatory and sales milestone payment	$ 300,000
Sirius Therapeutics [Member] \| Maximum [Member]
Contingencies And Commitments [Line Items]
Future development regulatory and sales milestone payment					300,000
Option payments					20,000
Milestones aggregate payment	$ 87,500				87,500
Letter of Credit [Member]
Contingencies And Commitments [Line Items]
Letters of credit secured by cash held in restricted depository account		8,000	11,500		8,000
2015 Collaboration Agreement [Member] \| Vertex Pharmaceuticals Incorporated and Certain of its Subsidiaries [Member]
Contingencies And Commitments [Line Items]
Milestone payment receivable		$ 395,000			395,000
Intellectual Property [Member]
Contingencies And Commitments [Line Items]
Research and development expense			$ 13,000		$ 3,800