Revenue - product sales and recycling services - Schedule of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Revenue	$ 8.4	$ 4.7	$ 21.0	$ 11.9
Product revenue
Disaggregation of Revenue [Line Items]
Product revenue recognized in the period	4.3	3.5	10.7	15.7
Fair value pricing adjustments	0.1	0.0	0.8	(6.0)
Revenue	4.4	3.5	11.5	9.7
Recycling service revenue recognized in the period
Disaggregation of Revenue [Line Items]
Revenue	$ 4.0	$ 1.2	$ 9.5	$ 2.2