Lease Accounting (Lease Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 4.4	$ 3.7	$ 12.4	$ 10.8
Finance lease cost
Amortization of leased assets	0.3	0.3	1.0	0.9
Interest on lease liabilities	0.0	0.0	0.1	0.1
Net lease costs	$ 4.7	$ 4.0	$ 13.5	$ 11.8