Revenue recognition - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Revenue	$ 231.1	$ 293.8	$ 594.2	$ 848.9
Commercial Product sales
Disaggregation of Revenue [Line Items]
Revenue	74.9	95.3	187.7	333.8
MCM Product sales
Disaggregation of Revenue [Line Items]
Revenue	142.5	174.2	357.5	393.0
All other revenue
Disaggregation of Revenue [Line Items]
Revenue	13.7	24.3	49.0	122.1
USG
Disaggregation of Revenue [Line Items]
Revenue	133.0	171.5	269.6	343.8
USG | Commercial Product sales
Disaggregation of Revenue [Line Items]
Revenue	0.7	0.0	2.0	0.4
USG | MCM Product sales
Disaggregation of Revenue [Line Items]
Revenue	123.2	161.8	235.8	319.7
USG | All other revenue
Disaggregation of Revenue [Line Items]
Revenue	9.1	9.7	31.8	23.7
Non-USG
Disaggregation of Revenue [Line Items]
Revenue	98.1	122.3	324.6	505.1
Non-USG | Commercial Product sales
Disaggregation of Revenue [Line Items]
Revenue	74.2	95.3	185.7	333.4
Non-USG | MCM Product sales
Disaggregation of Revenue [Line Items]
Revenue	19.3	12.4	121.7	73.3
Non-USG | All other revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 4.6	$ 14.6	$ 17.2	98.4
Janssen Pharmaceuticals, Inc., | Service
Disaggregation of Revenue [Line Items]
Revenue				$ 50.0