Commitments and Contingent Liabilities - Narrative (Details) $ in Millions	12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Number of Superfund sites designated potentially responsible party at	13
Accrual for environmental loss contingencies, net of related receivables	$ 56.3	$ 52.2
Asset retirement obligation, net of recoveries	21.5	21.6
Rental expense	$ 119.0	$ 120.3	$ 115.1