Leases - Operating Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Leases
Operating lease expense	$ 4.9	$ 14.3
Short-term lease expense	0.1	0.2
Variable lease expense	0.7	2.5
Total lease expense	$ 5.7	$ 17.0