Segment Information - Restructuring, Strategic Investment & Proxy Contest Charges (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) segment	Jun. 30, 2024 USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments | segment			3
Restructuring and other (income) charges, net	$ 21.9	$ 13.1	$ 34.2	$ 75.9
(Gain) loss on strategic investment	2.5	(0.1)	2.5	4.7
Performance Materials
Segment Reporting Information [Line Items]
Restructuring and other (income) charges, net	0.0	0.0	0.0	0.1
(Gain) loss on strategic investment	0.0	(0.1)	0.0	(0.1)
Performance Chemicals
Segment Reporting Information [Line Items]
Restructuring and other (income) charges, net	16.0	13.1	27.7	75.9
(Gain) loss on strategic investment	0.0	0.0	0.0	4.8
Advanced Polymer Technologies segment
Segment Reporting Information [Line Items]
Restructuring and other (income) charges, net	5.9	0.0	6.5	(0.1)
(Gain) loss on strategic investment	$ 2.5	$ 0.0	$ 2.5	$ 0.0