Derivative Financial Instruments (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Location and effect of the derivative instrument on the statements of operations
Amount of gain (loss) recognized	$ (438)	$ (616)	$ (1,179)	$ (244)
Hedged Item - Debt [Member] | Interest Expense, Net [Member]
Location and effect of the derivative instrument on the statements of operations
Amount of gain (loss) recognized	(788)	806	(1,409)	2,693
Interest Rate Swap [Member] | Interest Expense, Net [Member]
Location and effect of the derivative instrument on the statements of operations
Amount of gain (loss) recognized	$ 350	$ (1,422)	$ 230	$ (2,937)