Derivative Instruments (Details 1) (Foreign Exchange Contract [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue [Member]
Summary of the effect of derivatives designated as hedging instruments on the consolidated statements of income
Amount Reclassified from Accumulated Other Comprehensive Income into Income Gain/(Loss) (Effective Portion)	$ 0.1	$ 13.6	$ 1.2	$ 19.0
Other income (expense) [Member]
Summary of the effect of derivatives designated as hedging instruments on the consolidated statements of income
Gains and losses in earnings of Foreign currency forward contracts due to hedge ineffectiveness	$ 0.1	$ 1.3	$ 0.3	$ 3.2