Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 2.1	$ 2.1	$ 2.5
State	3.3	0.1	1.0
International	35.1	37.0	29.4
Current income tax provision	40.5	39.2	32.9
Deferred:
Federal and state	1.4	41.8	21.8
International	(0.5)	(0.1)	(0.3)
Deferred income tax provision	0.9	41.7	21.5
Income tax expense	$ 41.4	$ 80.9	$ 54.4