Annual report pursuant to Section 13 and 15(d)

Retirement Benefits - Postretirement Healthcare Plan (Details)

v3.19.3
Retirement Benefits - Postretirement Healthcare Plan (Details) - USD ($)
$ in Millions
 12 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2016
One-percentage-point increase/decrease in the assumed healthcare cost trend rates        
Accrued pension costs, long-term portion $ 131.3 $ 120.5    
Defined Benefit Plan, Funded (Unfunded) Status of Plan   (94.4)    
Other Postretirement Benefits Plan [Member]        
Retirement and Postemployment Benefits        
Other Postretirement Benefits Cost (Reversal of Cost) $ (0.1) $ 0.1 $ 0.3 $ 0.3
Weighted average assumptions used in revaluing obligation under the postretirement healthcare plan        
Discount rate for obligation (as a percent) 2.80% 4.00% 3.30%  
Healthcare cost rate assumed for next year (as a percent) 6.90% 7.10% 7.60%  
Ultimate trend rate (as a percent) 4.50% 4.50% 4.50%  
One-percentage-point increase/decrease in the assumed healthcare cost trend rates        
Impact of a one percentage point increase in healthcare cost trends on service and interest costs $ 0.0 $ 0.1    
Impact of a one percentage point decrease in healthcare cost trends on service and interest costs   0.1    
Impact of a one percentage point increase in healthcare cost trends on the benefit obligation 0.6 0.5    
Impact of a one percentage point decrease in healthcare cost trends on the benefit obligation   0.5    
Employer's expected annual future contribution to the postretirement healthcare plan 0.7      
Defined Benefit Plan, Benefit Obligation 8.2 7.6 $ 9.0  
Interest cost 0.3 0.2    
Service cost 0.2 0.3    
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) 1.0 (0.9)    
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31) 0.9 1.0    
Accrued pension costs, current portion 0.7 0.8    
Accrued pension costs, long-term portion 7.5 6.8    
Net amount recognized 8.2 7.6    
Domestic Plan [Member]        
Retirement and Postemployment Benefits        
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation $ 27.4 $ 25.7    
Weighted average assumptions used in revaluing obligation under the postretirement healthcare plan        
Discount rate for obligation (as a percent) 3.10% 4.20% 3.70%  
One-percentage-point increase/decrease in the assumed healthcare cost trend rates        
Defined Benefit Plan, Benefit Obligation $ 300.4 $ 267.0 $ 281.8  
Interest cost 9.8 8.7 8.8  
Service cost 2.3 2.7 3.6  
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) (37.1) 14.7    
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31) 14.1 11.5    
Accrued pension costs, current portion 2.0 2.0    
Accrued pension costs, long-term portion 25.5 23.7    
Defined Benefit Plan, Expected Return (Loss) on Plan Assets 13.3 14.0 13.7  
Amortization of unrecognized prior service cost, net (0.1) (0.2) (0.4)  
Defined Benefit Plan, Amortization of Gain (Loss) (1.2) (3.2) (3.6)  
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement (0.2) 0.0 (0.1)  
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) (0.3) (0.8) (2.8)  
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement 1.7 0.0    
Employee contributions 0.0 0.0    
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) 0.0 0.0    
Defined Benefit Plan, Plan Assets, Amount 280.6 253.3 $ 262.4  
Actual return on plan assets 39.6 0.6    
Employee and employer contributions 1.8 1.8    
Defined Benefit Plan, Plan Assets, Benefits Paid 14.1 11.5    
Effect of exchange rates on plan assets 0.0 0.0    
Defined Benefit Plan, Funded (Unfunded) Status of Plan (19.8) (13.7)    
Assets for Plan Benefits, Defined Benefit Plan 7.7 12.0    
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position (19.8) (13.7)    
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation 27.4 25.7    
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets 0.0 0.0    
Foreign Plan [Member]        
Retirement and Postemployment Benefits        
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation $ 102.3 $ 96.6    
Weighted average assumptions used in revaluing obligation under the postretirement healthcare plan        
Discount rate for obligation (as a percent) 0.30% 1.20% 1.10%  
One-percentage-point increase/decrease in the assumed healthcare cost trend rates        
Defined Benefit Plan, Benefit Obligation $ 137.8 $ 126.3 $ 133.4  
Interest cost 1.2 1.1 0.7  
Service cost 1.2 1.4 1.3  
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) (22.6) (0.4)    
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31) 5.7 5.2    
Accrued pension costs, current portion 6.0 6.6    
Accrued pension costs, long-term portion 98.3 90.0    
Defined Benefit Plan, Expected Return (Loss) on Plan Assets 0.5 0.6 0.5  
Amortization of unrecognized prior service cost, net 0.1 0.1 0.1  
Defined Benefit Plan, Amortization of Gain (Loss) (0.9) (0.7) (1.1)  
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement (0.4) 0.0 (0.6)  
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) 3.3 2.7 3.3  
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement 2.2 3.4    
Employee contributions 0.9 0.9    
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) 6.5 2.3    
Defined Benefit Plan, Plan Assets, Amount 33.5 31.9 $ 31.4  
Actual return on plan assets 1.5 (0.1)    
Employee and employer contributions 8.6 9.0    
Defined Benefit Plan, Plan Assets, Benefits Paid 5.7 5.2    
Defined Benefit Plan, Plan Assets, Payment for Settlement (2.2) (3.0)    
Effect of exchange rates on plan assets (0.6) (0.2)    
Defined Benefit Plan, Funded (Unfunded) Status of Plan (104.3)      
Assets for Plan Benefits, Defined Benefit Plan 0.0 2.2    
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position (104.3) (94.4)    
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation 102.3 96.6    
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets $ 0.0 $ 0.0    
Minimum [Member]        
One-percentage-point increase/decrease in the assumed healthcare cost trend rates        
Defined Contribution Plan, Employer Contribution Vesting Period 0 years      
Maximum [Member]        
One-percentage-point increase/decrease in the assumed healthcare cost trend rates        
Defined Contribution Plan, Employer Contribution Vesting Period 5 years