Financial Instruments and Risk Management (Effect of Derivative Instruments on the Consolidated Statements of Operations Derivatives in Fair Value Hedging Relationships) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in Earnings on Derivatives			$ 14.6
Amount of Gain or (Loss) Recognized in Earnings on Hedging Items			15.0
Fair value hedging relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in Earnings on Derivatives	$ (10.0)	$ 5.9	35.6
Amount of Gain or (Loss) Recognized in Earnings on Hedging Items	10.0	(5.9)	(27.0)
Fair value hedging relationships | Interest expense | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) or Gain Recognized in Earnings on Derivatives	(10.0)	5.9	35.6
Fair value hedging relationships | Interest expense | 2016 Senior Notes (1.800% coupon)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Hedging Items	0.0	0.0	(0.9)
Fair value hedging relationships | Interest expense | 2018 Senior Notes (6.000% coupon)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Hedging Items	0.0	0.0	4.6
Fair value hedging relationships | Interest expense | 2023 Senior Notes (3.125% coupon)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Hedging Items	$ 10.0	$ (5.9)	$ (45.7)