Leases - Schedule of Components of Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Lease Cost [Abstract]
Operating lease costs	$ 50.0	$ 150.0
Variable and short-term lease costs	25.6	79.6
Sublease income	(1.5)	(5.0)
Finance lease cost:
Amortization of lease assets	2.5	8.0
Interest on lease liabilities	1.9	6.0
Total lease cost, net	$ 78.5	$ 238.6