Derivative Financial Instruments Fair Value of the Company's Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Derivative Fair Value [Line Items]
Derivative asset, fair value, gross asset	$ 46,444	$ 4,482
Fair value of derivative liability	5,734	4,802
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Accrued expenses [Member]
Derivative Fair Value [Line Items]
Fair value of derivative liability	1,759	3,777
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other long-term liabilities [Member]
Derivative Fair Value [Line Items]
Fair value of derivative liability	148	882
Not Designated as Hedging Instrument [Member] | Cross-currency swap [Member] | Other long-term liabilities [Member]
Derivative Fair Value [Line Items]
Fair value of derivative liability	3,827	143
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Assets [Member]
Derivative Fair Value [Line Items]
Derivative asset, fair value, gross asset	29,327	4,227
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative Fair Value [Line Items]
Fair value of derivative liability	1,907	4,659
Fair Value, Inputs, Level 2 [Member] | Cross-currency swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative Fair Value [Line Items]
Fair value of derivative liability	3,827	143
Fair Value, Inputs, Level 2 [Member] | Cross-currency swap [Member] | Not Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivative Fair Value [Line Items]
Derivative asset, fair value, gross asset	$ 17,117	$ 255