Segment reporting - Summary of Segment Loss Including Segment Expenses (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting [Abstract]
Research, development, and laboratory		$ 45,696	$ 86,522	$ 112,567
Facility costs		44,253	49,429	54,778
Support functions		29,425	45,587	54,355
Stock-based compensation		25,464	37,678	35,533
Technical operations and manufacturing		21,813	39,713	52,359
Portfolio prioritization costs		318	5,840	5,203
Other	[1]	9,307	14,944	20,313
Research and development related success payments and contingent consideration		29,432	(8,881)	(48,981)
Impairment of long-lived assets		44,611	1,891	7,014
Total operating expenses		250,319	272,723	293,141
Loss from operations		(250,319)	(272,723)	(293,141)
Interest income, net		3,848	10,471	9,938
Other income (expense), net		2,305	(4,507)	(52)
Net loss		$ (244,166)	$ (266,759)	$ (283,255)
Segment reporting, other segment item, composition, description		Other segment expenses include licensing costs, consulting fees, business taxes, and insurance costs for the years ended December 31, 2025, 2024, and 2023, and costs incurred for the early termination of the Fremont lease for the year ended December 31, 2023.

[1] (1) Other segment expenses include licensing costs, consulting fees, business taxes, and insurance costs for the years ended December 31, 2025, 2024, and 2023, and costs incurred for the early termination of the Fremont lease for the year ended December 31, 2023.