Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. federal statutory tax rate (percent)	21.00%	35.00%
Discrete net tax expense related to Tax Act	$ 40.6		$ 221.2
Reversal of non-recurring benefit related to U.S. taxation of deemed foreign dividends	56.2
Tax benefit related to finalization of assessment of impacts of Tax Act	$ 15.6
Discrete net tax expense based on provisional estimates related to Tax Act		$ 206.5
Impact of new tax law on equity affiliate expense		$ 32.5	28.5
Tax expense for deemed repatriation tax and additional foreign taxes on repatriation of earnings			433.0
Tax expense for deemed repatriation tax			368.3
Tax expense for additional foreign taxes on repatriation of earnings			64.7
Tax benefit for re-measurement of net U.S. deferred tax liabilities at lower corporate tax rate			$ 211.8
Effective tax rate (percent)	27.00%	64.20%
Income tax payments, net of refunds	$ 28.7	$ 61.0