Foreign Currency Exchange Rate Risk Foreign Currency Exchange Rate Risk (Details textual) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative [Line Items]
Net gain (loss)	$ 2.6	$ (3.2)	$ 2.9	$ (7.9)
Maturities of foreign currency forward contracts	45 days or less		45 days or less