Financial instruments and financial risk factors - Assets and Liabilities Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Oct. 31, 2022	Oct. 31, 2021	Aug. 10, 2021	Oct. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts receivable (subject to provisional pricing)	$ 0.6	$ 1.2	$ 2.0	$ 2.8
Warrants	0.0	0.0	0.0	82.1	$ 48.3	$ 0.0
Conversion feature of convertible debt (refer to Note 17)	0.4	22.5	43.9	29.0
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts receivable (subject to provisional pricing)	0.0	0.0	0.0	0.0
Warrants				53.5
Conversion feature of convertible debt (refer to Note 17)	0.0	0.0	0.0	0.0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts receivable (subject to provisional pricing)	0.6	1.2	2.0	2.8
Warrants				28.6
Conversion feature of convertible debt (refer to Note 17)	$ 0.4	$ 22.5	$ 43.9	$ 29.0