Pension Plans - Schedule of Net Benefit Costs (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Interest cost	3.6	5.1	7.2	10.2
Expected return on plan assets	(3.3)	(5.3)	(6.6)	(10.5)
Amortization of unrecognized net losses	0.4	0.5	0.9	1.1
Net periodic cost	0.7	0.3	1.5	0.8
International
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.1	0.1	0.2	0.2
Interest cost	0.9	0.9	1.7	1.7
Expected return on plan assets	(0.9)	(0.7)	(1.7)	(1.4)
Amortization of unrecognized net losses	0.3	0.1	0.5	0.2
Net periodic cost	$ 0.4	$ 0.4	$ 0.7	$ 0.7