Income taxes - Schedule of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets
Tax losses and credits carryforwards	$ 113.1	$ 82.6
Share issuance costs	3.5	6.6
Convertible debt	0.0	0.0
Reserves and provisions	0.2	0.1
RIFE Pool	10.5	0.0
Other	3.5	2.8
Right of use assets, net of lease liabilities	0.4	0.9
Deferred income tax assets	131.2	93.0
Less valuation allowance	(100.0)	(68.9)
Deferred tax assets, net of valuation allowance	31.2	24.1
Deferred tax liabilities
Property, plant and equipment, due to differences in amortization	(6.6)	(8.0)
Convertible debt, due to differences in amortization	(24.6)	(16.1)
Deferred tax liabilities, net of valuation allowance	(31.2)	(24.1)
Net deferred income tax assets (liabilities)	$ 0.0	$ 0.0