v3.26.1
Pension Plans - Schedule of Net Benefit Costs (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Defined Benefit Plan Disclosure [Line Items]        
Settlement loss on U.K. pension plan termination $ 0.2 $ 0.0 $ 26.3 $ 0.0
U.S. | Pension Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 0.0 0.0 0.0 0.0
Interest cost 3.0 3.0 9.1 9.1
Expected return on plan assets (3.8) (4.0) (11.3) (11.9)
Amortization of unrecognized net losses 0.7 0.5 2.1 1.4
Settlement loss on U.K. pension plan termination 0.0 0.0 0.0 0.0
Net periodic (benefit)/cost (0.1) (0.5) (0.1) (1.4)
International | Pension Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 0.1 0.2 0.3 0.4
Interest cost 0.3 0.9 1.6 2.5
Expected return on plan assets (0.3) (0.9) (1.7) (2.6)
Amortization of unrecognized net losses 0.2 0.5 1.0 1.5
Settlement loss on U.K. pension plan termination 0.2 0.0 26.3 0.0
Net periodic (benefit)/cost $ 0.5 $ 0.7 $ 27.5 $ 1.8