Income Taxes (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred tax liability adjustment due to tax act		$ 8.6
Reduction to alternative minimum tax credit, percent		6.60%
Increase in unrecognized tax benefits		$ (0.9)
Tax settlement paid	$ 4.6
Unrecognized tax benefits that would impact effective tax rate	10.1	11.5	$ 10.1
Interest and penalty expense, excluding refunds		0.5	(1.1)	$ 0.6
Accrued interest and penalty	$ 2.4	$ 2.9	$ 2.4