GOODWILL (Details) $ in Millions	6 Months Ended
	Mar. 31, 2026 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 1,696.5
Segment recast	0.0
Goodwill acquired	2.7
Currency translation	(6.0)
Ending balance	1,693.2
Customized Polymer Solutions
Goodwill [Roll Forward]
Beginning balance	622.4
Segment recast	0.0
Goodwill acquired	2.7
Currency translation	(2.6)
Ending balance	622.5
Durable Metal Solutions
Goodwill [Roll Forward]
Beginning balance	418.7
Segment recast	31.3
Goodwill acquired	0.0
Currency translation	(2.2)
Ending balance	447.8
Sustainable Fiber Solutions
Goodwill [Roll Forward]
Beginning balance	475.9
Segment recast	52.4
Goodwill acquired	0.0
Currency translation	0.0
Ending balance	528.3
Innovative Closure Solutions
Goodwill [Roll Forward]
Beginning balance	179.5
Segment recast	(83.7)
Goodwill acquired	0.0
Currency translation	(1.2)
Ending balance	$ 94.6