Goodwill and Other Intangible Assets, net - Carrying Amount (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Goodwill [Roll Forward]
Goodwill, beginning balance			$ 175.2
Foreign currency translation			12.9
Goodwill impairment charge	$ (183.8)	$ (349.1)	(183.8)	$ (349.1)
Goodwill, ending balance	4.3		4.3
Performance Materials
Goodwill [Roll Forward]
Goodwill, beginning balance			4.3
Foreign currency translation			0.0
Goodwill impairment charge			0.0
Goodwill, ending balance	4.3		4.3
Performance Chemicals
Goodwill [Roll Forward]
Goodwill, beginning balance			0.0
Foreign currency translation			0.0
Goodwill impairment charge			0.0
Goodwill, ending balance	0.0		0.0
Impairment loss					$ 349.1
Advanced Polymer Technologies segment
Goodwill [Roll Forward]
Goodwill, beginning balance			170.9
Foreign currency translation			12.9
Goodwill impairment charge			(183.8)
Goodwill, ending balance	$ 0.0		$ 0.0