Business combinations, dispositions and related transactions - Components of Net Distributions from LPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Summary Of Investment Holdings [Line Items]
Distributions from LPC	$ 31.2	$ 52.8	$ 58.3
Contributions to LPC	(33.9)	(49.7)	(68.8)
Net distributions (contributions)	(2.7)	$ 3.1	$ (10.5)
Louisiana Pigment Company, L.P. (LPC)
Summary Of Investment Holdings [Line Items]
Income (loss) from equity investments	$ 0.0