Retirement Plans - Schedule of Amounts in Accumulated Other Comprehensive (Income) Loss (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Pension Plan [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	$ 753.2	$ 854.7
Prior service cost (credit)	45.6	27.6
Total accumulated other comprehensive loss (income)	798.8	882.3
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	188.6	168.8
Prior service cost (credit)	2.4	3.4
Total accumulated other comprehensive loss (income)	191.0	172.2
Other Postretirement Benefits Plan [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	(10.6)	(8.0)
Prior service cost (credit)	(5.7)	(8.3)
Total accumulated other comprehensive loss (income)	(16.3)	(16.3)
Other Postretirement Benefits Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	13.0	18.8
Prior service cost (credit)	1.2	(0.9)
Total accumulated other comprehensive loss (income)	$ 14.2	$ 17.9