Derivative Instruments Derivative Instruments Affecting the Consolidated Statements of Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in Income on Derivative	$ 9.1	$ 0
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in OCI on Derivative (Effective Portion)	0	(0.5)
Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(0.2)	0
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0
Interest Rate Swaps [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in OCI on Derivative (Effective Portion)	0	(0.5)
Interest Rate Swaps [Member] | Interest Expense [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(0.2)	0
Foreign Currency Forward Contract [Member] | Foreign Exchange Gain [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in Income on Derivative	$ 9.1	$ 0