Nature of business and future operations (Details)	3 Months Ended
	Mar. 31, 2026 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash	$ 95,200,000
Long-term debt	$ 0
Genevant Sciences Corporation
Gain Contingencies [Line Items]
Ownership interest in equity method investment (as a percentage)	16.00%
Revenue from collaborations and licenses | Genevant
Gain Contingencies [Line Items]
Company's interest in settlement amount, percent	20.00%
Moderna | Revenue from collaborations and licenses | Genevant
Gain Contingencies [Line Items]
Noncontingent settlement amount	$ 950,000,000.0
Revenue recognized as portion of Settlement Agreement	178,700,000
Additional noncontingent settlement amount pending	$ 1,300,000,000