Convertible debt - Schedule of Glencore PIK Notes (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Oct. 31, 2022	May 31, 2022	Oct. 31, 2021	Oct. 31, 2020
Glencore Convertible Notes
Debt Conversion [Line Items]
Amount Issued	$ 225.3
Glencore Convertible Notes | Convertible Debt
Debt Conversion [Line Items]
Amount Issued	225.3	$ 208.1	$ 200.0		$ 0.0	$ 0.0
Initial Glencore Note | Convertible Debt
Debt Conversion [Line Items]
Amount Issued	200.0			$ 200.0
Glencore PIK Note, Issued November 30, 2022 | Convertible Debt
Debt Conversion [Line Items]
Amount Issued	8.1
Glencore PIK Note, Issued May 31, 2023 | Convertible Debt
Debt Conversion [Line Items]
Amount Issued	8.4
Glencore PIK Note, Issued November 30, 2023 | Convertible Debt
Debt Conversion [Line Items]
Amount Issued	$ 8.8