Other Comprehensive Income (Loss) (Schedule of Tax Effects) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit/(provision) for income taxes allocated to other comprehensive income (loss) items	$ 151.0	$ (30.3)	$ 402.7
Foreign Currency Translation Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit/(provision) for income taxes allocated to other comprehensive income (loss) items	(18.4)	51.6	170.8
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	(7.4)	2.1	55.0
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	184.1	(85.3)	186.6
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	$ (7.3)	$ 1.3	$ (9.7)