Income taxes - Components of the Provisions for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current
Federal	$ (0.6)	$ (9.4)	$ (3.1)
State	0.5	1.9	14.9
International	36.7	33.8	28.9
Total current	36.6	26.3	40.7
Deferred
Federal	(2.0)	(37.7)	37.1
State	(1.2)	(3.2)	4.2
International	(4.1)	7.2	1.6
Total deferred	(7.3)	(33.7)	43.0
Income tax (benefit) provision	$ 29.3	$ (7.4)	$ 83.7

Amount of current federal tax expense (benefit) attributable to income (loss) from continuing operations. Includes, but is not limited to, current national tax expense (benefit) for non-US (United States of America) jurisdiction.

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