Leases - Operating Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2020
Leases
Operating lease expense	$ 4.8	$ 9.4
Short-term lease expense	0.1	0.1
Variable lease expense	0.7	1.8
Total lease expense	$ 5.6	$ 11.3