Accumulated Other Comprehensive Loss (Schedule of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		$ (154.8)
OCI before reclassifications	[1]	48.9	$ 18.1
Reclassification to earnings		(3.9)	(2.9)
Ending Balance		(109.8)	(154.8)
Stockholders' Equity Attributable to Parent		1,553.1	1,584.1	$ 1,540.5	$ 1,467.1
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications	[1]	27.0	18.6
Reclassification to earnings		0.0	0.0
Stockholders' Equity Attributable to Parent		(41.3)	(68.3)	(86.9)
Pension and Post-retirement Activity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications	[1]	19.0	0.1
Reclassification to earnings		(1.8)	1.1
Stockholders' Equity Attributable to Parent		(67.6)	(84.8)	(86.0)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' Equity Attributable to Parent		(0.9)	(1.7)	2.9
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications	[1]	2.9	(0.6)
Reclassification to earnings		(2.1)	(4.0)
Accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' Equity Attributable to Parent		$ (109.8)	$ (154.8)	$ (170.0)	$ (216.1)

[1] OCI is defined as other comprehensive income.