Derivatives Foreign Currency Forward Contracts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivatives, Fair Value [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ 221	$ 126	$ 83
30 Day Forward Contract EURO [Member]
Derivatives, Fair Value [Line Items]
Derivative, Currency Bought	12	658
30 Day Forward Contract GBP [Member]
Derivatives, Fair Value [Line Items]
Derivative, Currency Bought	328	222