Derivative Instruments and Hedging Activities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Forward Foreign Exchange Contracts [Member]
Value of intercompany receivable and payables hedged by forward foreign exchange contracts	$ 192.4	$ 1,351.8
Notional value of forward foreign exchange contracts to purchase currencies	96.2	679.5
Notional value of forward foreign exchange contracts to sell currencies	96.2	672.3
Forward foreign exchange contracts, terms	The terms of our forward contracts are generally less than 90 days.
Interest Rate Swap [Member]
Reduction of interest expense from interest rate swaps	$ 12.2	$ 5.0