Supplemental Information (Payables and Accrued Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Disclosure Text Block Supplement [Abstract]
Trade creditors	$ 546.2	$ 528.2
Contract liabilities	313.8	247.4
Dividends payable	296.2	255.7
Accrued payroll and employee benefits	196.8	186.1
Obligation for future contribution to an equity affiliate	94.4	94.4
Current lease obligations	70.7
Derivative instruments	50.9	91.2
Pension and postretirement benefits	17.9	26.0
Other	246.3	206.7
Payables and accrued liabilities	$ 1,833.2	$ 1,635.7