Fair Value of Financial Instruments and Concentration of Credit Risk (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Level 1 | Interest rate hedge agreements [Member]
Summary of derivatives held by the company
Assets (Liabilities) Measured at Fair Value	$ 0	$ 0
Level 1 | Foreign currency hedge agreements
Summary of derivatives held by the company
Assets (Liabilities) Measured at Fair Value	0	0
Level 2 | Interest rate hedge agreements [Member]
Summary of derivatives held by the company
Assets (Liabilities) Measured at Fair Value	(3,988)	(3,960)
Level 2 | Foreign currency hedge agreements
Summary of derivatives held by the company
Assets (Liabilities) Measured at Fair Value	(393)	(28)
Level 3 | Interest rate hedge agreements [Member]
Summary of derivatives held by the company
Assets (Liabilities) Measured at Fair Value	0	0
Level 3 | Foreign currency hedge agreements
Summary of derivatives held by the company
Assets (Liabilities) Measured at Fair Value	0	0
Carrying Value on Consolidated Balance Sheets | Interest rate hedge agreements [Member]
Summary of derivatives held by the company
Assets (Liabilities) Measured at Fair Value	(3,988)	(3,960)
Carrying Value on Consolidated Balance Sheets | Foreign currency hedge agreements
Summary of derivatives held by the company
Assets (Liabilities) Measured at Fair Value	$ (393)	$ (28)