Annual report pursuant to Section 13 and 15(d)

Retirement Benefits - Postretirement Healthcare Plan (Details)

v3.10.0.1
Retirement Benefits - Postretirement Healthcare Plan (Details) - USD ($)
$ in Millions
12 Months Ended
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 $ 120.5 $ 129.6  
Defined Benefit Plan, Funded (Unfunded) Status of Plan   (102.0)  
Other Postretirement Benefits Plan [Member]      
Retirement and Postemployment Benefits      
Other Postretirement Benefits Cost (Reversal of Cost) $ 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) 4.00% 3.30% 3.10%
Healthcare cost rate assumed for next year (as a percent) 7.10% 7.60% 7.30%
Ultimate trend rate (as a percent) 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 $ 0.1    
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 0.5    
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 0.8    
Defined Benefit Plan, Benefit Obligation 7.6 $ 9.0 $ 10.3
Interest cost 0.2 0.2  
Service cost 0.3 0.4  
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) (0.9) (0.9)  
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31) 1.0 1.0  
Accrued pension costs, current portion 0.8 0.8  
Accrued pension costs, long-term portion 6.8 8.2  
Net amount recognized 7.6 9.0  
Domestic Plan [Member]      
Retirement and Postemployment Benefits      
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation $ 25.7 $ 27.7  
Weighted average assumptions used in revaluing obligation under the postretirement healthcare plan      
Discount rate for obligation (as a percent) 4.20% 3.70% 3.60%
One-percentage-point increase/decrease in the assumed healthcare cost trend rates      
Defined Benefit Plan, Benefit Obligation $ 267.0 $ 281.8 $ 294.2
Interest cost 8.7 8.8 9.5
Service cost 2.7 3.6 3.9
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) 14.7 6.9  
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31) 11.5 11.0  
Accrued pension costs, current portion 2.0 1.8  
Accrued pension costs, long-term portion 23.7 25.8  
Defined Benefit Plan, Expected Return (Loss) on Plan Assets 14.0 13.7 9.7
Amortization of unrecognized prior service cost, net (0.2) (0.4) (0.6)
Defined Benefit Plan, Amortization of Gain (Loss) (3.2) (3.6) (3.8)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement 0.0 (0.1) 0.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) (0.8) (2.8) (8.1)
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement 0.0 6.9  
Employee contributions 0.0 0.0  
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) 0.0 0.0  
Defined Benefit Plan, Fair Value of Plan Assets 253.3 262.4 $ 173.7
Actual return on plan assets 0.6 17.9  
Employee and employer contributions 1.8 81.8  
Defined Benefit Plan, Plan Assets, Benefits Paid 11.5 11.0  
Effect of exchange rates on plan assets 0.0 0.0  
Defined Benefit Plan, Funded (Unfunded) Status of Plan (13.7) (19.4)  
Assets for Plan Benefits, Defined Benefit Plan 12.0 8.2  
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position (13.7) (19.4)  
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation 25.7 27.6  
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Fair Value of 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 $ 96.6 $ 102.0  
Weighted average assumptions used in revaluing obligation under the postretirement healthcare plan      
Discount rate for obligation (as a percent) 1.20% 1.10% 1.00%
One-percentage-point increase/decrease in the assumed healthcare cost trend rates      
Defined Benefit Plan, Benefit Obligation $ 126.3 $ 133.4 $ 140.9
Interest cost 1.1 0.7 1.8
Service cost 1.4 1.3 1.8
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) (0.4) 9.5  
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31) 5.2 5.7  
Accrued pension costs, current portion 6.6 6.8  
Accrued pension costs, long-term portion 90.0 95.6  
Defined Benefit Plan, Expected Return (Loss) on Plan Assets 0.6 0.5 1.0
Amortization of unrecognized prior service cost, net 0.1 0.1 0.1
Defined Benefit Plan, Amortization of Gain (Loss) (0.7) (1.1) (0.3)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement 0.0 (0.6) (0.5)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) 2.7 3.3 3.5
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement 3.4 1.2  
Employee contributions 0.9 0.8  
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) 2.3 (6.1)  
Defined Benefit Plan, Fair Value of Plan Assets 31.9 31.4 $ 29.7
Actual return on plan assets (0.1) 0.3  
Employee and employer contributions 9.0 8.5  
Defined Benefit Plan, Plan Assets, Benefits Paid 5.2 5.7  
Defined Benefit Plan, Plan Assets, Payment for Settlement (3.0) (1.6)  
Effect of exchange rates on plan assets (0.2) 0.2  
Defined Benefit Plan, Funded (Unfunded) Status of Plan (94.4)    
Assets for Plan Benefits, Defined Benefit Plan 2.2 0.4  
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position (94.4) (102.0)  
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation 96.6 102.0  
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Fair Value of Plan Assets $ 0.0 $ 0.0