Segment Information - Net Sales and Segment Operating Profit (Details) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information, Profit (Loss)
Segment EBITDA	$ 110,000,000.0		$ 101,300,000		$ 201,300,000	$ 178,200,000
Interest expense, net	(18,600,000)		(23,200,000)		(38,000,000.0)	(45,500,000)
(Provision) benefit for income taxes	(3,800,000)		50,900,000		(10,100,000)	66,800,000
Depreciation and amortization	(25,600,000)		(27,300,000)		(50,500,000)	(56,900,000)
Restructuring and other income (charges), net	(21,900,000)		(13,100,000)		(34,200,000)	(75,900,000)
Goodwill impairment charge	183,800,000		349,100,000		183,800,000	349,100,000
Acquisition and other-related income (costs), net	0		200,000		0	(100,000)
Inventory charges	0		0		0	(2,500,000)
Loss on CTO resales	0		(23,500,000)		0	(50,000,000.0)
Gain (loss) on strategic investments	(2,500,000)		100,000		(2,500,000)	(4,700,000)
Proxy contest charges	(300,000)		0		(8,200,000)	0
Net income (loss)	(146,500,000)	$ 20,500,000	(283,700,000)	$ (56,000,000.0)	(126,000,000.0)	(339,700,000)
Performance Materials
Segment Reporting Information, Profit (Loss)
Segment EBITDA	77,100,000		82,200,000		156,200,000	160,200,000
Depreciation and amortization	(9,900,000)		(9,700,000)		(19,800,000)	(19,300,000)
Goodwill impairment charge					0
Gain (loss) on strategic investments	0		100,000		0	100,000
Performance Chemicals
Segment Reporting Information, Profit (Loss)
Segment EBITDA	32,000,000.0		9,300,000		31,700,000	(1,300,000)
Depreciation and amortization	(7,400,000)		(10,100,000)		(14,700,000)	(22,500,000)
Goodwill impairment charge					0
Gain (loss) on strategic investments	0		0		0	(4,800,000)
Advanced Polymer Technologies
Segment Reporting Information, Profit (Loss)
Segment EBITDA	900,000		9,800,000		13,400,000	19,300,000
Depreciation and amortization	(8,300,000)		(7,500,000)		(16,000,000.0)	(15,100,000)
Goodwill impairment charge					183,800,000
Gain (loss) on strategic investments	$ (2,500,000)		$ 0		$ (2,500,000)	$ 0