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RESTRUCTURING ACTIVITIES - Asset Restructuring Plan (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		54 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026
RESTRUCTURING ACTIVITIES
Accretion expense			$ 1.9
2022 Asset restructuring plan
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges	$ 0.3	$ 0.7	0.5	$ (7.1)	$ 55.3
Change in cost estimate of asset retirement obligation				(8.1)
Activities
Reserve balance at December 31, 2025			0.5
Restructuring charges (credits)			0.5
Payments			(1.0)
2022 Asset restructuring plan \| Engineered Materials
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges				(0.3)
2022 Asset restructuring plan \| Polymer Solutions
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges	0.3	0.7	0.5	(6.8)
2022 Asset restructuring plan \| Severance and related benefit credits (credits)
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges	(0.1)		(0.1)	(0.3)	8.5
Activities
Reserve balance at December 31, 2025			0.5
Restructuring charges (credits)			(0.1)
Payments			(0.4)
2022 Asset restructuring plan \| Asset related charges (credits)
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges			0.1	(8.1)	33.3
Activities
Restructuring charges (credits)			0.1
Payments			(0.1)
2022 Asset restructuring plan \| Accelerated depreciation for the asset retirement cost
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges					17.1
2022 Asset restructuring plan \| Accelerated depreciation charges of plant, property and equipment associated with the exit
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges					7.7
2022 Asset restructuring plan \| Decommissioning and other charges
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges					8.5
2022 Asset restructuring plan \| Contract terminations
RESTRUCTURING ACTIVITIES
Net pre-tax restructuring charges	0.4	$ 0.7	0.5	$ 1.3	13.5
Restructuring costs expected to incur	1.7		1.7		1.7
Activities
Restructuring charges (credits)			0.5
Payments			(0.5)
2022 Asset restructuring plan \| Employee termination benefits
Activities
Reserve balance at December 31, 2025			0.5
Reserve balance at June 30, 2026	$ 0.0		$ 0.0		$ 0.0