Leases - Schedule of Components of Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2020
Lease Cost [Abstract]
Operating lease costs	$ 50.5	$ 100.0
Variable and short-term lease costs	27.7	54.0
Sublease income	(1.8)	(3.5)
Finance lease cost:
Amortization of lease assets	2.7	5.5
Interest on lease liabilities	2.0	4.1
Total lease cost, net	$ 81.1	$ 160.1