Changes in Accumulated Other Comprehensive Loss (Schedule of Reclassifications from Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income and expense	$ (7.1)	$ (8.8)	$ (11.3)
Net income	629.9	813.0	$ 184.5
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income and expense	(3.3)	(0.4)
Net income	$ (3.3)	$ (0.4)