Income Taxes (Schedule of Components of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 20.3	$ (24.3)	$ (1.3)
State	0.6	0.2	2.8
Foreign	126.8	114.2	97.8
Current income tax expense (benefit)	147.7	90.1	99.3
Deferred:
Federal	0.9	21.9	(19.0)
State	0.0	0.0	0.0
Foreign	(15.0)	(19.8)	(7.8)
Deferred income tax expense (benefit)	(14.1)	2.1	(26.8)
Income tax provision	$ 133.6	$ 92.2	$ 72.5