Derivative Instruments and Hedging Activities (Details) (USD $) In Millions, unless otherwise specified			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Forward Foreign Exchange Contracts [Member]
Forward foreign exchange contracts, intercompany borrowings and investments, aggregate notional principal	$ 181.5	$ 120.8
Forward foreign exchange contracts, revenue and expenses, aggregate notional principal	$ 63.6	$ 71.6
Forward foreign exchange contracts, terms			The terms of our forward contracts are generally less than 90 days.