Financial Instruments (Narrative) (Details) In Millions, unless otherwise specified	12 Months Ended					12 Months Ended		12 Months Ended		12 Months Ended
	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2012 Forward Contracts PHP [Member] PHP	Dec. 31, 2012 Forward Contracts PHP [Member] USD ($)	Dec. 31, 2012 Forward Contracts INR [Member] INR	Dec. 31, 2012 Forward Contracts INR [Member] USD ($)	Dec. 31, 2012 Forward Contracts COP [Member] COP	Dec. 31, 2012 Forward Contracts COP [Member] USD ($)	Dec. 31, 2012 Forward Contracts AUD [Member] AUD	Dec. 31, 2012 Forward Contracts AUD [Member] USD ($)
Derivatives
Foreign currency acquired through forward exchange contracts				15,360.0		9,792.5		35,700.0
Notional amount, foreign currency derivatives	590.4	619.8			349.6		176.6		18.4		45.7
Foreign currency sold through forward exchange contracts										44.7
Derivative instruments maturity period (in months)	36 months
Deferred tax expense	7.1	(1.0)
Deferred gains (losses), net of tax	11.4	(1.5)
Deferred gain on derivative instruments reclassified from OCI to earnings during the next the next twelve months, before tax	10.4
Deferred gain on derivative instruments reclassified from OCI to earnings during next twelve months, net of tax	6.5
Net gain related to forward contracts	14.8	11.6
Net loss related to settlement of forward contracts			(0.5)
Net loss recognized, related to changes in fair value	(0.4)	(0.2)
Aggregate fair value of derivative instruments in liability positions	9.5
Aggregate fair value of collateral already posted	0
Trading Securities, Fair Value Disclosure	19.5
Short-term time desposits	$ 64.3