Equity Investments (Summary Of The Difference Between Carrying Amount And Underlying Equity OF Equity Method Investment) (Details) - WAVE [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Total of fair value adjustments to assets	$ 161.0	$ 166.6
Property, Plant and Equipment [Member]
Schedule of Equity Method Investments [Line Items]
Total of fair value adjustments to assets	0.4	0.4
Other Intangibles [Member]
Schedule of Equity Method Investments [Line Items]
Total of fair value adjustments to assets	130.2	135.8
Goodwill [Member]
Schedule of Equity Method Investments [Line Items]
Total of fair value adjustments to assets	$ 30.4	$ 30.4