Income Taxes (Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Income tax expense computed at U.S. statutory income tax rate (21% and 35%, respectively)	$ 10.3	$ 17.5	$ 20.8	$ 30.8
Interest on Brazilian Tax Assessment	0.3	0.5	0.9	1.8
Partial release of reserve for the Brazilian Tax Assessment	0.0	0.0	(5.6)	0.0
Excess tax benefit from stock-based compensation	0.0	0.0	(2.6)	(5.5)
Net operating losses not benefited	0.8	0.0	2.8	0.0
Foreign tax rate change	0.0	0.0	3.9	0.0
Foreign earnings taxed at higher (lower) rate	3.3	0.0	5.7	(2.6)
Non-deductible expenses related to acquisitions	0.0	1.1	0.0	1.7
Miscellaneous tax expense (benefit)	(1.3)	0.1	1.5	4.1
Income tax expense as reported	$ 13.4	$ 19.2	$ 27.4	$ 30.3
Effective Income Tax Rate Reconciliation, Percent	27.30%	38.60%	27.60%	34.40%