Derivative Instruments (Details 1) - Foreign Exchange Contract - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows, revenue | Revenue
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)	$ (32.5)	$ 5.3	$ 173.2
Cash flows, revenue | Other income (expense)
Summary of the effect of derivatives designated as hedging instruments on the consolidated statements of income
Net gains (losses) in earnings of foreign currency forward contracts due to hedge ineffectiveness	8.9	2.9	4.9
Cash flows, operating expenses | Other income (expense)
Summary of the effect of derivatives designated as hedging instruments on the consolidated statements of income
Net gains (losses) in earnings of foreign currency forward contracts due to hedge ineffectiveness	(0.2)	0.1	0.0
Cash flows, operating expenses | Operating Expense
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)	$ 0.6	$ (1.5)	$ 0.0