Segment Information - Net Economic Earnings to Net Income (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Abstract]
Net Income	$ 271.7	$ 250.9	$ 217.5
Fair value and timing adjustments	(10.4)	(12.4)	11.4
Acquisition and restructuring activities	15.2	7.6	2.5
Income tax adjustments	(1.0)	1.3	(3.3)
Adjusted Earnings	$ 275.5	$ 247.4	$ 228.1