Other Comprehensive Income (Loss) (Schedule of Tax Effects) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit/(provision) for income taxes allocated to other comprehensive income (loss) items	$ 200.9	$ 151.0	$ (30.3)
Foreign Currency Translation Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit/(provision) for income taxes allocated to other comprehensive income (loss) items	128.3	(18.4)	51.6
Unrealized Net Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit/(provision) for income taxes allocated to other comprehensive income (loss) items	(4.3)	(7.4)	2.1
Defined Benefit Pension and Retiree Health Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit/(provision) for income taxes allocated to other comprehensive income (loss) items	44.8	184.1	(85.3)
Effective Portion of Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit/(provision) for income taxes allocated to other comprehensive income (loss) items	$ 32.1	$ (7.3)	$ 1.3