Significant agreements - Novartis Collaboration Agreement (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Mar. 27, 2023 item
Significant agreements.
Revenue from collaborative arrangement	$ 11,734	$ 2,676	$ 24,631	$ 31,567
Deferred revenue	86,380		86,380		$ 101,658	$ 135,194
Novartis
Significant agreements.
Number of collaboration targets \| item							2
Revenue from collaborative arrangement	2,181	1,276	5,077	$ 6,301
Deferred revenue	$ 42,133		$ 42,133		$ 44,073	$ 50,008
Novartis \| Expiration of two material rights associated with limited substitution rights
Significant agreements.
Revenue from collaborative arrangement		$ 2,500
Novartis \| Revenue allocated per identified performance obligations recognized
Significant agreements.
Material rights exercise period			3 years
Novartis \| Revenue allocated to material rights upon exercise or expiration of the respective options
Significant agreements.
Material rights exercise period			6 years

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

BICYCLE THERAPEUTICS PLC 10-Q