Segment Information - Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Segment Reporting Information [Line Items]
Personnel-related expenses		$ 23,590	$ 14,928
Stock-based compensation epxense		28,880	20,380
Change in fair value of related party revenue share liability		2,570	1,430
Interest income		(12,862)	(11,835)
Other segment items	[1]	14,336	7,004
Income tax provision		168	157
Net loss		(109,279)	(84,582)	$ (425,400)
Zidesamtinib[Member]
Segment Reporting Information [Line Items]
Direct external expenses by program		12,309	15,551
Neladalkib [Member]
Segment Reporting Information [Line Items]
Direct external expenses by program		26,316	28,007
NVL-330 [Member]
Segment Reporting Information [Line Items]
Direct external expenses by program		6,826	3,961
Discovery Programs [Member]
Segment Reporting Information [Line Items]
Direct external expenses by program		2,803	2,133
General and Administrative Expenses [Member]
Segment Reporting Information [Line Items]
Stock-based compensation epxense		12,777	8,949
General and administrative professional and consultant fees		$ 4,343	$ 2,866

[1] Other segment items included in consolidated net loss include expenses for commercialization preparation activities, research and development consulting services, information technology, employee recruitment, and other miscellaneous activities.