Derivative Financial Instruments (Details 2) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	$ 21,277	$ 16,751
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	8,422	9,119
Designated as Hedging Instrument [Member] | Accrued expenses [Member] | Interest rate swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	4,271	4,202
Designated as Hedging Instrument [Member] | Other long-term liabilities [Member] | Interest rate swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	4,151	4,917
Cross-currency swap [Member] | Not Designated as Hedging Instrument [Member] | Accrued expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	5,778	5,541
Cross-currency swap [Member] | Not Designated as Hedging Instrument [Member] | Other long-term liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	7,077	2,091
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability	$ 12,855	$ 7,632