Derivative Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	$ 14,195	$ 16,751
Derivatives designated as hedges [Member] | Accrued expenses [Member] | Interest rate swap agreement [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	4,143	4,202
Derivatives designated as hedges [Member] | Other long-term liabilities [Member] | Interest rate swap agreement [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	2,882	4,917
Derivatives not designated as hedges [Member] | Accrued expenses [Member] | Cross-currency swap agreement [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	7,170	5,541
Derivatives not designated as hedges [Member] | Other long-term liabilities [Member] | Cross-currency swap agreement [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	0	2,091
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Derivatives designated as hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	7,025	9,119
Cross-currency swap agreement [Member] | Fair Value, Inputs, Level 2 [Member] | Derivatives not designated as hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	$ 7,170	$ 7,632