Income Taxes, 2017 Tax Cuts and Jobs Act (Details) $ in Millions		3 Months Ended	12 Months Ended
	Dec. 31, 2017 item	Dec. 31, 2017 USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
U.S. statutory federal tax rate (as a percent)				35.00%	35.00%	35.00%
Estimated Tax Act Charge		$ 398.5
Estimated Transition Tax		259.4
Provisional charge on unremitted foreign earnings		176.6
Income tax expense (benefit) associated with the remeasurement of net deferred tax liabilities		$ (37.5)
Number of components | item	3
Forecast
U.S. statutory federal tax rate (as a percent)			21.00%
Period for payment of Transition Tax			8 years