Revenue - product sales and recycling services - Movement In Deferred Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2024	Dec. 31, 2023
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue	$ 0.6		$ 0.6	$ 0.2
Non-current deferred revenue	5.3		5.3	5.3
Product revenue
Movement in Deferred Revenue [Roll Forward]
Balance, beginning of the period	0.0	$ 0.0	0.0	0.0
Additions			3.4	0.0
Foreign exchange revaluation	0.0	0.0	(2.8)	0.0
Balance, end of the period	0.6	0.0	0.6	0.0
Current deferred revenue	0.6		0.6	0.0
Non-current deferred revenue	0.0		0.0	0.0
Service
Movement in Deferred Revenue [Roll Forward]
Balance, beginning of the period		$ 5.5	5.5	0.0
Additions			0.0	5.4
Amounts recognized in product revenue			0.0	0.0
Foreign exchange revaluation			(0.2)	0.1
Balance, end of the period	5.3		5.3	5.5
Current deferred revenue	0.0		0.0	0.2
Non-current deferred revenue	$ 5.3		$ 5.3	$ 5.3