Income Taxes (Summary of Income Tax Uncertainties) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Liability at beginning of year, net	$ 3.0	$ 2.7	$ 3.0
Additions for tax positions of current year	0.0	0.9	0.4
Subtractions as a result of a lapse of the applicable statute of limitations	0.0	(0.6)	(0.7)
Liability at end of year, net	$ 3.0	$ 3.0	$ 2.7