Financial Instruments and Risk Management (Effect Of Derivative Instruments on the Condensed Consolidated Statements of Operations Derivatives in Fair Value Hedging Relationships) (Details) - Fair Value Hedging Relationships - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	$ 3.3	$ (5.0)	$ 24.3	$ (27.3)
Amount of Gain (Loss) Recognized in Earnings on Hedged Items	(3.3)	5.0	(24.3)	27.3
Interest expense | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	3.3	(5.0)	24.3	(27.3)
Interest expense | 2023 Senior Notes (3.125% coupon)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Earnings on Hedged Items	$ (3.3)	$ 5.0	$ (24.3)	$ 27.3