Pension Benefit Obligations - Schedule of Components of Net Periodic Cost for Pension Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
U.S.
Defined Benefit Plan Disclosure [Line Items]
Service costs	$ 0.0	$ 0.0
Interest cost on projected benefit obligation	2.0	2.4
Expected return on plan assets	(1.2)	(1.4)
Amortization of net loss (gain)	0.9	0.8
Net periodic benefit cost (credit)	1.7	1.8
Int’l
Defined Benefit Plan Disclosure [Line Items]
Service costs	0.0	0.1
Interest cost on projected benefit obligation	9.9	10.7
Expected return on plan assets	(12.8)	(14.1)
Amortization of net loss (gain)	(0.3)	(0.6)
Net periodic benefit cost (credit)	$ (3.2)	$ (3.9)