RESTRUCTURING CHARGES - Amounts Expected to be Incurred, Amounts Incurred, and Amounts Remaining to Be Incurred (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	$ 44.6		$ 44.6
Amounts Incurred During the Six Months Ended March 31, 2026	10.8	$ 9.1	19.0	$ 12.4
Amounts Remaining to be Incurred	25.6		25.6
Employee separation costs
Restructuring and Related Costs [Line Items]
Amounts Incurred During the Six Months Ended March 31, 2026	7.8		12.3
Other restructuring costs
Restructuring and Related Costs [Line Items]
Amounts Incurred During the Six Months Ended March 31, 2026	3.0		6.7
Customized Polymer Solutions
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	3.3		3.3
Amounts Incurred During the Six Months Ended March 31, 2026			2.8
Amounts Remaining to be Incurred	0.5		0.5
Customized Polymer Solutions | Employee separation costs
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	2.5		2.5
Amounts Incurred During the Six Months Ended March 31, 2026			2.0
Amounts Remaining to be Incurred	0.5		0.5
Customized Polymer Solutions | Other restructuring costs
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	0.8		0.8
Amounts Incurred During the Six Months Ended March 31, 2026			0.8
Amounts Remaining to be Incurred	0.0		0.0
Durable Metal Solutions
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	12.8		12.8
Amounts Incurred During the Six Months Ended March 31, 2026			5.1
Amounts Remaining to be Incurred	7.7		7.7
Durable Metal Solutions | Employee separation costs
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	5.5		5.5
Amounts Incurred During the Six Months Ended March 31, 2026			3.5
Amounts Remaining to be Incurred	2.0		2.0
Durable Metal Solutions | Other restructuring costs
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	7.3		7.3
Amounts Incurred During the Six Months Ended March 31, 2026			1.6
Amounts Remaining to be Incurred	5.7		5.7
Sustainable Fiber Solutions
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	28.1		28.1
Amounts Incurred During the Six Months Ended March 31, 2026			11.0
Amounts Remaining to be Incurred	17.1		17.1
Sustainable Fiber Solutions | Employee separation costs
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	8.2		8.2
Amounts Incurred During the Six Months Ended March 31, 2026			6.7
Amounts Remaining to be Incurred	1.5		1.5
Sustainable Fiber Solutions | Other restructuring costs
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	19.9		19.9
Amounts Incurred During the Six Months Ended March 31, 2026			4.3
Amounts Remaining to be Incurred	15.6		15.6
Innovative Closure Solutions
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	0.4		0.4
Amounts Incurred During the Six Months Ended March 31, 2026			0.1
Amounts Remaining to be Incurred	0.3		0.3
Innovative Closure Solutions | Employee separation costs
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	0.4		0.4
Amounts Incurred During the Six Months Ended March 31, 2026			0.1
Amounts Remaining to be Incurred	0.3		0.3
Innovative Closure Solutions | Other restructuring costs
Restructuring and Related Costs [Line Items]
Total Amounts Expected to be Incurred	0.0		0.0
Amounts Incurred During the Six Months Ended March 31, 2026			0.0
Amounts Remaining to be Incurred	$ 0.0		$ 0.0