Asset retirement obligations - Narrative (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Oct. 31, 2022	Oct. 31, 2021
Asset Retirement Obligation [Line Items]
Asset retirement obligation, restoration assets, carrying value	$ 0.2	$ 0.7	$ 0.3	$ 0.2
Asset retirement obligation, restoration assets, amortization	$ 0.0	0.1	$ 0.1	$ 0.1
Accrual for environmental loss contingencies, gross		$ 1.6
Minimum
Asset Retirement Obligation [Line Items]
Accrual for environmental loss contingencies, discount rate		0.37%
Maximum
Asset Retirement Obligation [Line Items]
Accrual for environmental loss contingencies, discount rate		10.96%