Income taxes - Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Oct. 31, 2022	Oct. 31, 2021
Income Tax Disclosure [Abstract]
Net (loss) income before taxes	$ 1.6	$ (137.9)	$ (50.3)	$ (70.5)
Statutory tax rates	26.50%	26.50%	26.50%	26.50%
Federal statutory income tax rate, amount	$ 0.4	$ (36.5)	$ (13.3)	$ (18.7)
Income tax	0.0	0.1	0.0	0.0
Change in valuation allowance	(1.2)	26.1	17.6	8.8
Rate differential	0.3	3.0	0.5	0.0
Effective Income Tax Rate Reconciliation, Internal Transfer Of Intangible Property, Amount	0.0	4.0	0.0	0.0
Other	0.0	0.1	0.1	0.0
Non-deductible item and others	0.5	3.4	(4.9)	9.9
Income tax expense	$ 0.0	$ 0.1	$ 0.0	$ 0.0