Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 56.8	$ 54.4	$ 95.5	$ 70.8
Effective income tax rate reconciliation, percent	24.70%	27.90%	24.10%	26.20%