Other assets - Schedule of Other Assets (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Non-current security deposits	$ 5.0	$ 5.0
Non-current insurance	0.1	2.8
Intangible assets, net	1.7	1.8
Other assets	$ 6.8	$ 9.6