Summary of Significant Accounting Policies - Goodwill (Details) - USD ($) $ in Millions		12 Months Ended
	Jul. 01, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Changes in the carrying amount of goodwill
Goodwill, Beginning Balance		$ 1,835.7	$ 2,028.1
Impairment charges		(82.3)	(238.0)
Divestiture of Milacron		(180.0)
Acquisition measurement period adjustments			(1.3)
Foreign currency adjustments		28.0	46.9
Goodwill, Ending Balance		1,601.4	1,835.7	$ 2,028.1
Goodwill and Intangible Asset Impairment [Abstract]
Goodwill, impairment loss		82.3	238.0
Total		83.5	265.0	0.0
Trade Names
Goodwill
Trade names, indefinite lives		175.3	197.4
Goodwill and Intangible Asset Impairment [Abstract]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		1.2	27.0
Molding Technology Solutions
Goodwill
Trade names, indefinite lives		60.5	85.1
Changes in the carrying amount of goodwill
Goodwill, Beginning Balance		405.5	633.2
Impairment charges	$ (82.3)	(82.3)	(238.0)
Divestiture of Milacron		(180.0)
Acquisition measurement period adjustments			0.0
Foreign currency adjustments		(0.6)	10.3
Goodwill, Ending Balance		142.6	405.5	633.2
Impairment charges	1.2
Goodwill and Intangible Asset Impairment [Abstract]
Goodwill, impairment loss	$ 82.3	82.3	238.0
Impairment of Intangible Assets (Excluding Goodwill)			$ 27.0
ImpairmentIntangibleAssetStatementOfIncomeOrComprehensiveIncomeExtensibleEnumerationNotDisclosedFlag			impairment charge
Advanced Process Solutions
Changes in the carrying amount of goodwill
Goodwill, Beginning Balance		1,430.2	$ 1,394.9
Impairment charges		0.0	0.0
Divestiture of Milacron		0.0
Acquisition measurement period adjustments			(1.3)
Foreign currency adjustments		28.6	36.6
Goodwill, Ending Balance		1,458.8	1,430.2	$ 1,394.9
Goodwill and Intangible Asset Impairment [Abstract]
Goodwill, impairment loss		$ 0.0	$ 0.0