Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Provision for (benefit from) income taxes	$ 24.8	$ 18.0
Increase (Decrease) in Income Taxes	6.8
Tax Cuts and Jobs Act of 2017 GILTI Provisional Tax Expense	5.9
Other Tax Expense (Benefit)	$ 1.6	$ 2.5
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%		35.00%