Annual report pursuant to Section 13 and 15(d)

Retirement Benefits - Postretirement Healthcare Plan (Details)

v3.20.2
Retirement Benefits - Postretirement Healthcare Plan (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2018
One-percentage-point increase/decrease in the assumed healthcare cost trend rates          
Accrued pension costs, long-term portion $ 166.8 $ 131.3 $ 166.8 $ 131.3  
Defined Benefit Plan, Funded (Unfunded) Status of Plan   $ (104.3)   (104.3)  
Other Postretirement Benefits Plan          
Retirement and Postemployment Benefits          
Other Postretirement Benefits Cost (Reversal of Cost)     $ 0.1 $ (0.1) $ 0.1
Weighted average assumptions used in revaluing obligation under the postretirement healthcare plan          
Discount rate for obligation (as a percent) 2.10% 2.80% 2.10% 2.80% 4.00%
Healthcare cost rate assumed for next year (as a percent) 6.60% 6.90% 6.60% 6.90% 7.10%
Ultimate trend rate (as a percent) 4.50% 4.50% 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   0.7    
Defined Benefit Plan, Benefit Obligation 8.5 $ 8.2 8.5 8.2 $ 7.6
Interest cost     0.2 0.3  
Service cost     0.2 0.2  
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)     2.0 1.0  
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31)     2.1 0.9  
Accrued pension costs, current portion 0.7 0.7 0.7 0.7  
Accrued pension costs, long-term portion 7.8 7.5 7.8 7.5  
Net amount recognized 8.5 8.2 8.5 8.2  
Domestic Plan          
Retirement and Postemployment Benefits          
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation $ 27.7 $ 27.4 $ 27.7 $ 27.4  
Weighted average assumptions used in revaluing obligation under the postretirement healthcare plan          
Discount rate for obligation (as a percent) 2.60% 3.10% 2.60% 3.10% 4.20%
One-percentage-point increase/decrease in the assumed healthcare cost trend rates          
Defined Benefit Plan, Benefit Obligation $ 316.6 $ 300.4 $ 316.6 $ 300.4 $ 267.0
Projected benefit obligation attributable to acquisitions     0.0 0.0  
Interest cost     8.0 9.8 8.7
Service cost     1.4 2.3 2.7
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)     (20.6) (37.1)  
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31)     13.8 14.1  
Accrued pension costs, current portion 2.0 2.0 2.0 2.0  
Accrued pension costs, long-term portion 25.7 25.5 25.7 25.5  
Defined Benefit Plan, Expected Return (Loss) on Plan Assets     12.8 13.3 14.0
Amortization of unrecognized prior service cost, net     0.0 (0.1) (0.2)
Defined Benefit Plan, Amortization of Gain (Loss)     (4.8) (1.2) (3.2)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement     0.0 (0.2) 0.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)     (1.4) (0.3) (0.8)
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement     0.0 1.7  
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 297.9 280.6 297.9 280.6 $ 253.3
Fair value of pension assets attributable to acquisitions     0.0 0.0  
Actual return (loss) on plan assets     29.3 39.6  
Employee and employer contributions     1.8 1.8  
Defined Benefit Plan, Plan Assets, Benefits Paid     13.8 14.1  
Effect of exchange rates on plan assets     0.0 0.0  
Defined Benefit Plan, Funded (Unfunded) Status of Plan (18.7) (19.8) (18.7) (19.8)  
Assets for Plan Benefits, Defined Benefit Plan 9.0 7.7 9.0 7.7  
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position (18.7) (19.8) (18.7) (19.8)  
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation 27.7 27.4 27.7 27.4  
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets 0.0 0.0 0.0 0.0  
Foreign Plan          
Retirement and Postemployment Benefits          
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation $ 184.8 $ 102.3 $ 184.8 $ 102.3  
Weighted average assumptions used in revaluing obligation under the postretirement healthcare plan          
Discount rate for obligation (as a percent) 0.60% 0.30% 0.60% 0.30% 1.20%
One-percentage-point increase/decrease in the assumed healthcare cost trend rates          
Defined Benefit Plan, Benefit Obligation $ 184.8 $ 137.8 $ 184.8 $ 137.8 $ 126.3
Projected benefit obligation attributable to acquisitions     (37.7) 0.0  
Interest cost     0.6 1.2 1.1
Service cost     1.9 1.2 1.4
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)     (2.3) (22.6)  
Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31)     3.4 5.7  
Accrued pension costs, current portion 8.1 6.0 8.1 6.0  
Accrued pension costs, long-term portion 133.3 98.3 133.3 98.3  
Defined Benefit Plan, Expected Return (Loss) on Plan Assets     0.8 0.5 0.6
Amortization of unrecognized prior service cost, net     0.1 0.1 0.1
Defined Benefit Plan, Amortization of Gain (Loss)     (2.5) (0.9) (0.7)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement     (1.0) (0.4) 0.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)     5.3 3.3 2.7
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement     4.7 2.2  
Employee contributions     1.0 0.9  
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)     (11.6) 6.5  
Defined Benefit Plan, Plan Assets, Amount 43.8 33.5 43.8 33.5 $ 31.9
Fair value of pension assets attributable to acquisitions     7.6 0.0  
Actual return (loss) on plan assets     (1.1) 1.5  
Employee and employer contributions     9.2 8.6  
Defined Benefit Plan, Plan Assets, Benefits Paid     3.4 5.7  
Defined Benefit Plan, Plan Assets, Payment for Settlement 0.0 0.0 (4.7) (2.2)  
Effect of exchange rates on plan assets     2.7 (0.6)  
Defined Benefit Plan, Funded (Unfunded) Status of Plan (141.0)   (141.0)    
Assets for Plan Benefits, Defined Benefit Plan 0.5 0.0 0.5 0.0  
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position (140.9) (104.3) (140.9) (104.3)  
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation 180.9 102.3 180.9 102.3  
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets $ 43.8 $ 0.0 $ 43.8 $ 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