Pension Benefit Obligations - Schedule of Reconciliations of Changes In the U.S. and International Plans' Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
U.S.
Change in benefit obligation:
Benefit obligation at beginning of year	$ 186.9	$ 181.2	$ 198.1
Service cost	0.0	0.0	0.0
Participant contributions	0.1	0.1	0.1
Interest cost	7.9	9.7	9.8
Benefits and expenses paid	(17.1)	(17.6)	(17.2)
Actuarial loss (gain)	(0.2)	13.5	(8.8)
Plan settlements	(0.7)	0.0	(1.5)
Transfers in	0.0	0.0	0.7
Foreign currency translation loss	0.0	0.0	0.0
Benefit obligation at end of year	176.9	186.9	181.2
Int’l
Change in benefit obligation:
Benefit obligation at beginning of year	860.4	756.2	791.2
Service cost	0.2	0.2	0.3
Participant contributions	0.2	0.3	0.2
Interest cost	40.1	43.7	47.7
Benefits and expenses paid	(46.2)	(47.7)	(42.2)
Actuarial loss (gain)	(69.8)	37.0	(112.5)
Plan settlements	0.0	(3.2)	(1.5)
Transfers in	0.0	0.0	0.0
Foreign currency translation loss	4.4	73.9	73.0
Benefit obligation at end of year	$ 789.3	$ 860.4	$ 756.2