Revenue - product sales and recycling services - Schedule of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Revenue	$ 8.4	$ 3.6	$ 12.6	$ 7.2
Product revenue
Disaggregation of Revenue [Line Items]
Product revenue recognized in the period	5.0	4.8	6.4	12.0
Fair value pricing adjustments	0.2	(1.7)	0.7	(5.8)
Revenue	5.2	3.1	7.1	6.2
Recycling service revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 3.2	$ 0.5	$ 5.5	$ 1.0