Segment and Geographical Information - Segment adjusted EBITDA to consolidated net income (Details) - USD ($) $ in Millions		12 Months Ended
	Jul. 01, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Segment and Geographical Information
Adjusted EBITDA		$ 388.0	$ 511.7	$ 483.2
Interest expense, net		94.5	121.5	77.7
Income tax (benefit) expense		(54.5)	64.8	102.8
Depreciation and amortization		138.5	158.0	125.6
Pension settlement (gain) charges		1.7	(35.2)	0.0
Gain on sale of property, plant, and equipment		0.0	36.0	0.0
Consolidated net income (loss)		52.1	(202.0)	576.7
Total income from discontinued operations		0.0	2.2	462.6
Gain on sale leaseback transactions		33.7
Corporate
Segment and Geographical Information
Adjusted EBITDA		(56.6)	(53.8)	(59.6)
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment
Segment and Geographical Information
Interest expense, net		94.5	121.5	77.7
Income tax (benefit) expense		(54.5)	64.8	102.8
Depreciation and amortization		138.5	158.0	125.6
Impairment charges		83.5	265.0	0.0
Pension settlement (gain) charges		(1.7)	35.2	0.0
Business acquisition, divestiture, and integration costs		65.1	72.2	46.2
Restructuring and restructuring-related charges		21.4	26.2	5.1
Gain on sale of property, plant, and equipment		0.0	33.7	0.0
Inventory step-up costs		$ 0.0	$ 0.6	$ 11.7
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Statement of Income or Comprehensive Income [Extensible Enumeration]		Gain (Loss) on Disposition of Business	Gain (Loss) on Disposition of Business	Gain (Loss) on Disposition of Business
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		$ 57.2	$ 0.0	$ 0.0
Other non-recurring costs related to a discrete commercial dispute		0.0	6.1	0.0
Other		(68.1)	0.0	0.0
Advanced Process Solutions | Operating Segments
Segment and Geographical Information
Adjusted EBITDA		345.5	423.2	355.7
Molding Technology Solutions
Segment and Geographical Information
Impairment charges	$ 1.2
Molding Technology Solutions | Operating Segments
Segment and Geographical Information
Adjusted EBITDA		$ 99.1	$ 142.3	$ 187.1