INCOME TAXES - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Deferred tax assets to be netted with deferred tax liabilities:
U.S. intangible asset	$ 14.4	$ 3.9
Net operating loss carryforwards	24.0	22.3
Excess interest expense	84.1	63.0
Foreign tax credit	39.5	39.4
Stock-based compensation	1.3	2.1
Research and development costs	3.6	4.3
Federal and state capital losses	3.5	3.6
Right of use lease liability	13.5	12.7
State tax credits	9.5	8.9
Inventory	6.7	7.3
Other, net	15.9	18.1
Total deferred tax assets before valuation allowance	216.0	185.6
Valuation allowance	(198.9)	(167.3)
Total deferred tax assets to be netted with deferred tax liabilities	17.1	18.3
Deferred tax liabilities:
Property, plant and equipment	51.1	53.9
Foreign intangible asset	3.8	4.3
Right of use lease asset	13.1	12.7
Unrealized foreign exchange gain	1.1	1.2
Other, net	1.9	2.7
Total deferred tax liabilities	71.0	74.8
Net deferred tax liabilities	$ 53.9	$ 56.5