Leases - Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lease Cost
Amortization of Right-of-Use Assets - Finance Leases	$ 0.1	$ 0.0	$ 0.2	$ 0.2
Operating Lease Cost	5.8	5.1	16.8	15.9
Variable Lease, Cost	0.0		0.1
Short-Term Lease Cost	0.8	0.0	2.4	0.0
Total Lease Expense	6.7	5.1	19.5	16.1
Less: Sublease Income	0.2	0.0	0.2
Lease, Cost	$ 6.5	$ 5.1	$ 19.3	$ 16.1