BUSINESS SEGMENT INFORMATION - Properties, Plants and Equipment, Net by Geographical Area (Details) - USD ($) $ in Millions	Mar. 31, 2026	Sep. 30, 2025
Assets:
Total assets	$ 5,596.6	$ 5,766.8
Property, plant and equipment, net and lease right-of-use assets:
Total long-lived assets, net	1,328.2	1,355.8
United States
Property, plant and equipment, net and lease right-of-use assets:
Total long-lived assets, net	796.3	814.7
Europe, Middle East and Africa
Property, plant and equipment, net and lease right-of-use assets:
Total long-lived assets, net	378.0	392.2
Asia Pacific and Other Americas
Property, plant and equipment, net and lease right-of-use assets:
Total long-lived assets, net	153.9	148.9
Operating Segments
Assets:
Total assets	5,052.5	5,308.5
Operating Segments | Customized Polymer Solutions
Assets:
Total assets	1,878.5	1,872.9
Operating Segments | Durable Metal Solutions
Assets:
Total assets	1,247.6	1,196.8
Operating Segments | Sustainable Fiber Solutions
Assets:
Total assets	1,705.5	1,917.1
Operating Segments | Innovative Closure Solutions
Assets:
Total assets	220.9	321.7
Corporate and other
Assets:
Total assets	$ 544.1	$ 458.3