Convertible debt - Schedule of Glencore Convertible Notes Valuation Assumptions (Details) - Glencore Convertible Notes	Jun. 30, 2024	Dec. 31, 2023	May 31, 2022
Risk free interest rate
Debt Conversion [Line Items]
Embedded derivative liability, measurement input		0.042	0.029
Risk free interest rate | Minimum
Debt Conversion [Line Items]
Embedded derivative liability, measurement input	0.043
Risk free interest rate | Maximum
Debt Conversion [Line Items]
Embedded derivative liability, measurement input	0.053
Expected life of options
Debt Conversion [Line Items]
Embedded derivative liability, measurement input		4.4	5
Expected life of options | Minimum
Debt Conversion [Line Items]
Embedded derivative liability, measurement input	4.7
Expected life of options | Maximum
Debt Conversion [Line Items]
Embedded derivative liability, measurement input	6.9
Expected dividend yield
Debt Conversion [Line Items]
Embedded derivative liability, measurement input	0.000	0.000	0.000
Expected stock price volatility
Debt Conversion [Line Items]
Embedded derivative liability, measurement input	0.71	0.63	0.68
Share Price
Debt Conversion [Line Items]
Embedded derivative liability, measurement input	6.53	4.76	8.15