v3.23.1
Pension Plans - Schedule of Net Benefit Costs (Details) - Pension Plan - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 31, 2023
Mar. 31, 2022
Mar. 31, 2023
Mar. 31, 2022
U.S.        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 0.0 $ 0.0 $ 0.0 $ 0.0
Interest cost 5.1 3.2 10.2 6.4
Expected return on plan assets (5.3) (5.7) (10.5) (11.4)
Amortization of unrecognized net losses 0.5 1.6 1.1 3.2
Net periodic cost/(benefit) 0.3 (0.9) 0.8 (1.8)
International        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 0.1 0.2 0.2 0.4
Interest cost 0.9 0.4 1.7 0.9
Expected return on plan assets (0.7) (0.9) (1.4) (1.7)
Amortization of unrecognized net losses 0.1 0.3 0.2 0.4
Net periodic cost/(benefit) $ 0.4 $ 0.0 $ 0.7 $ 0.0