Income Taxes (Components of Income Before Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic operations	$ 68.7	$ 33.9	$ 60.9
Foreign operations	89.4	91.2	70.5
Income before income tax	$ 158.1	$ 125.1	$ 131.4