Financial Instruments and Risk Management (Effect Of Derivative Instruments on the Condensed Consolidated Statements of Operations Derivatives in Fair Value Hedging Relationships) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Document Fiscal Year Focus			2018
Fair Value Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	$ (5.0)	$ (2.5)	$ (27.3)	$ (1.0)
Amount of Gain (Loss) Recognized in Earnings on Hedged Items	5.0	2.5	27.3	1.0
Fair Value Hedging Relationships | Interest expense | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	(5.0)	(2.5)	(27.3)	(1.0)
Fair Value Hedging Relationships | Interest expense | 2023 Senior Notes (3.125% coupon)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Hedged Items	$ 5.0	$ 2.5	$ 27.3	$ 1.0