Segment Information - Capital Expenditures (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Total capital expenditures	$ 12.2	$ 18.1	$ 22.2	$ 34.7
Performance Materials
Segment Reporting Information [Line Items]
Total capital expenditures	6.9	9.3	12.0	16.6
Performance Chemicals
Segment Reporting Information [Line Items]
Total capital expenditures	1.6	5.7	2.8	11.9
Advanced Polymer Technologies segment
Segment Reporting Information [Line Items]
Total capital expenditures	$ 3.7	$ 3.1	$ 7.4	$ 6.2