v3.20.4
Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Gain) (Details) - USD ($)
$ in Millions
 3 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Pension Benefits | North America    
Components of net periodic benefit cost (gain)    
Service cost $ 0.9 $ 1.1
Interest cost 0.8 0.9
Expected return on plan assets (1.6) (1.6)
Recognized net actuarial loss 0.6 0.5
Net periodic benefit cost (gain) 0.7 0.9
Pension Benefits | Other International    
Components of net periodic benefit cost (gain)    
Interest cost 3.7 3.7
Expected return on plan assets (6.0) (6.2)
Recognized prior service cost (credit) 0.1 0.0
Net periodic benefit cost (gain) (2.2) (2.5)
Other Postretirement Benefit Plan | North America    
Components of net periodic benefit cost (gain)    
Service cost 0.1 0.1
Interest cost 0.4 0.5
Recognized net actuarial loss 0.3 0.2
Recognized prior service cost (credit) (1.2) (1.2)
Net periodic benefit cost (gain) $ (0.4) $ (0.4)