Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Foreign currency forward contracts that were entered into to hedge forecasted revenue
Total foreign currency forward contracts	$ 524.0	$ 532.3
Foreign Exchange Contract | Other Current Assets | Designated as Hedging Instrument
Summary of derivatives designated as hedging instruments
Asset derivatives	0.6	32.6
Foreign Exchange Contract | Accrued Liabilities | Designated as Hedging Instrument
Summary of derivatives designated as hedging instruments
Liability derivatives	11.5	0
Euro
Foreign currency forward contracts that were entered into to hedge forecasted revenue
Total foreign currency forward contracts	492.2	496.4
Canadian Dollar
Foreign currency forward contracts that were entered into to hedge forecasted revenue
Total foreign currency forward contracts	31.8	22.9
Swedish krona
Foreign currency forward contracts that were entered into to hedge forecasted revenue
Total foreign currency forward contracts	$ 0	$ 13.0