Summary of Significant Accounting Policies (Details 6) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Balance at the beginning of the period	$ 2,489	$ (5,666)	$ (24,225)
Change during period	514	8,155	18,559
Balance at the end of the period	3,003	2,489	(5,666)
Unrealized (Loss) Gain on Interest Rate Swap Agreements
Balance at the beginning of the period		(8,842)	(26,623)
Change during period		8,842	17,781
Balance at the end of the period			(8,842)
Foreign Currency Translation Adjustment
Balance at the beginning of the period	2,489	3,176	2,398
Change during period	514	(687)	778
Balance at the end of the period	$ 3,003	$ 2,489	$ 3,176