Other assets - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Oct. 31, 2022	Oct. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 2.0	$ 0.4	$ 0.3	$ 0.0
Less - accumulated amortization	(0.2)	0.0	0.0	0.0
Intangible assets, net	1.8	0.4	0.3	0.0
Internal-use software
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	0.7	0.0	0.0	0.0
Cloud computing arrangements
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 1.3	$ 0.4	$ 0.3	$ 0.0