Prepayments, deposits and other current assets - Schedule of Prepaids (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid equipment deposits	$ 1.0	$ 40.1
Prepaid transaction costs	11.1	7.8
Prepaid lease deposits	5.3	5.6
Prepaid insurance	4.5	4.6
Prepaid construction charges	0.9	2.6
Other prepaids	3.7	3.3
Total prepayments, deposits and other current assets	26.5	64.0
Non-current security deposits	(5.0)	(5.0)
Non-current insurance	(0.1)	(2.8)
Prepayments, deposits and other current assets	$ 21.4	$ 56.2