Derivative Financial Instruments Fair Value of the Company's Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivative Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 10,274	$ 4,482
Fair value of derivative liability	3,475	4,802
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Accrued expenses [Member]
Derivative Fair Value [Line Items]
Fair value of derivative liability	2,521	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	789	882
Not Designated as Hedging Instrument [Member] | Cross-currency swap [Member] | Accrued expenses [Member]
Derivative Fair Value [Line Items]
Fair value of derivative liability	16	0
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	149	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	10,274	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	3,310	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	165	143
Fair Value, Inputs, Level 2 [Member] | Cross-currency swap [Member] | Not Designated as Hedging Instrument [Member] | Prepaid expenses and other [Member]
Derivative Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 0	$ 255