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]
Income tax rate at which the deferred tax assets and liabilities are expected to reverse			21.00%
Tax Cuts And Jobs Act Of 2017, incomplete accounting, change in tax rate, deferred tax asset, provisional income tax expense			$ 41.1
Tax Cuts And Jobs Act Of 2017, incomplete accounting, transition tax for accumulated foreign earnings, provisional tax	$ 290.0
Effective income tax rate, percent	283.30%	164.90%
Income tax provision from discontinued operations		$ 126.9
Excess tax benefits on share-based compensation		$ 9.3
Increase in effective foreign income tax rate	3.60%