BUSINESS SEGMENT INFORMATION - Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Depreciation, depletion and amortization expense:
Total depreciation, depletion and amortization expense	$ 60.3	$ 67.5
Continuing Operations
Depreciation, depletion and amortization expense:
Total depreciation, depletion and amortization expense	60.3	58.5
Capital Expenditure [Abstract]
Total capital expenditures	35.2	30.7
Continuing Operations | Operating Segments
Capital Expenditure [Abstract]
Total capital expenditures	32.0	28.6
Continuing Operations | Corporate and other
Capital Expenditure [Abstract]
Total capital expenditures	3.2	2.1
Customized Polymer Solutions | Continuing Operations
Depreciation, depletion and amortization expense:
Total depreciation, depletion and amortization expense	27.9	23.0
Customized Polymer Solutions | Continuing Operations | Operating Segments
Capital Expenditure [Abstract]
Total capital expenditures	11.2	9.9
Durable Metal Solutions | Continuing Operations
Depreciation, depletion and amortization expense:
Total depreciation, depletion and amortization expense	7.6	7.2
Durable Metal Solutions | Continuing Operations | Operating Segments
Capital Expenditure [Abstract]
Total capital expenditures	6.9	6.8
Sustainable Fiber Solutions | Continuing Operations
Depreciation, depletion and amortization expense:
Total depreciation, depletion and amortization expense	23.4	26.6
Sustainable Fiber Solutions | Continuing Operations | Operating Segments
Capital Expenditure [Abstract]
Total capital expenditures	10.4	11.4
Innovative Closure Solutions | Continuing Operations
Depreciation, depletion and amortization expense:
Total depreciation, depletion and amortization expense	1.4	1.7
Innovative Closure Solutions | Continuing Operations | Operating Segments
Capital Expenditure [Abstract]
Total capital expenditures	$ 3.5	$ 0.5