Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective tax rates	31.00%	38.00%
Gross unrecognized tax benefits	$ 19.1		$ 17.1
Reduction in provision for income taxes due to impact of effective tax rate	14.5
Deferred tax assets classified as other current assets	196.3		$ 180.6
Income tax benefits attributable to the exercise of employee stock options recorded directly to Additional paid-in-capital	11.3	$ 28.8
Increase in unrecognized tax benefits is reasonably possible	15.3
Accrued Expenses [Member]
Gross unrecognized tax benefits	$ 3.8