Basis of Presentation - Noncontrolling Interest (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Provision for/(benefit from) income taxes	$ 289.0	$ (540.0)
Effective tax rate (as a percent)	15.40%	(47.50%)
Tax charge resulting from additional U.S. tax reform guidelines	$ 129.0
Other (income) and expense
Noncontrolling interest amounts, net of tax	$ 7.0	$ 7.8