Leases (Details) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	$ 14.2	$ 14.2
Operating Lease, Weighted Average Remaining Lease Term	4 years 6 months	4 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent	3.80%	3.80%
Operating Leases, Rent Expense	$ 8.0	$ 16.2
Operating Lease, Payments	$ 9.2	17.9
Facilities
Lessee, Lease, Description [Line Items]
Sublease Income		$ 2.3