Fair Values of Financial Instruments Schedule of Fair Values of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 91,474	$ 133,086	$ 129,514	$ 169,477
Cash and cash equivalents, at fair value	91,474	133,086
Foreign exchange forwards, asset	57	241
Liabilities
Foreign exchange forwards, liability	103	222
Interest Rate Swaps	2,697	0
2011 Senior Secured Credit Facility [Member] | USD Denominated Term Loan [Member]
Liabilities
Term loans	281,250	292,502
Term loans, at fair value	278,963	296,856
2011 Senior Secured Credit Facility [Member] | Line of Credit [Member]
Liabilities
Line of Credit Facility, Amount Outstanding	140,000	160,000
Line of Credit Facility, Fair Value of Amount Outstanding	138,676	163,269
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Foreign exchange forwards, asset, at fair value	57	241
Liabilities
Foreign exchange forwards, liability, at fair value	103	222
Interest Rate Derivative Liabilities, at Fair Value	$ 2,697	$ 0