Leases - Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lease Cost
Amortization of Right-of-Use Assets - Finance Leases	$ 0.0	$ 0.2	$ 0.2	$ 0.5
Operating Lease Cost	5.1	4.3	15.9	15.5
Short-Term Lease Cost	0.0	0.0	0.0	0.1
Total Expense	5.1	4.5	16.1	16.1
Less: Sublease Income	0.0	0.0	0.0	0.1
Total Lease Cost	$ 5.1	$ 4.5	$ 16.1	$ 16.0