Business combinations, dispositions and related transactions - Components of Net Distributions from LPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Summary Of Investment Holdings [Line Items]
Distributions from LPC		$ 31.2	$ 52.8
Contributions to LPC		(33.9)	(49.7)
Net distributions (contributions)		$ (2.7)	$ 3.1
Louisiana Pigment Company, L.P. (LPC)
Summary Of Investment Holdings [Line Items]
Income (loss) from equity investments	$ 0.0