Business combinations, dispositions and related transactions - Summary of Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Financial Information [Line Items]
Current assets	$ 1,453.7	$ 1,475.4
Property and equipment, net	723.4	517.3	$ 523.8
Total assets	2,800.2	2,737.0	2,835.7
Other liabilities, primarily current	17.1	30.1
Total liabilities and equity	2,800.2	2,737.0
Net sales	2,166.6	1,977.1	2,266.2
Cost of sales	1,680.3	1,676.5	1,732.1
General and administrative	256.2	277.4	304.0
Total costs and other expense	1,922.4	1,996.6	2,096.3
Net income	$ 161.3	5.1	133.1
Louisiana Pigment Company, L.P. (LPC)
Financial Information [Line Items]
Current assets		118.5
Property and equipment, net		148.4
Total assets		266.9
Other liabilities, primarily current		42.1
Partners' equity		224.8
Total liabilities and equity		266.9
Net sales		463.4	451.5
Cost of sales		463.0	451.1
General and administrative		0.4	0.4
Total costs and other expense		463.4	451.5
Louisiana Pigment Company, L.P. (LPC) | Kronos
Financial Information [Line Items]
Net sales		231.7	225.6
Louisiana Pigment Company, L.P. (LPC) | Venator
Financial Information [Line Items]
Net sales		$ 231.7	$ 225.9