Fair Values of Financial Instruments Schedule of Fair Values of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 102,800	$ 133,086	$ 168,284	$ 169,477
Cash and cash equivalents, at fair value	102,800	133,086
Foreign exchange forwards, asset	762	241
Liabilities
Foreign exchange forwards, liability	730	222
Interest Rate Swaps	1,365	0
2011 Senior Secured Credit Facility [Member] | USD Denominated Term Loan [Member]
Liabilities
Term loans	285,000	292,502
Term loans, at fair value	282,530	296,856
2011 Senior Secured Credit Facility [Member] | Line of Credit [Member]
Liabilities
Line of Credit Facility, Amount Outstanding	170,000	160,000
Line of Credit Facility, Fair Value of Amount Outstanding	168,284	163,269
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Foreign exchange forwards, asset, at fair value	762	241
Liabilities
Foreign exchange forwards, liability, at fair value	730	222
Interest Rate Derivative Liabilities, at Fair Value	$ 1,365	$ 0