Segment reporting - Schedule of Geographical Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 774.3	$ 737.0
Revenue	28.0	18.3
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	41.5	57.0
Revenue	0.3	1.0
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	693.4	618.9
Revenue	19.8	16.3
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	26.2	34.9
Revenue	7.9	0.0
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	13.2	26.2
Revenue	$ 0.0	$ 1.0