Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective tax rate	4.40%	41.40%
Net unrecognized tax benefit	$ 81.1		$ 77.8
Income tax interest and penalties accrued	3.4
Deferred tax assets	$ 101.1