Accounting for Interest Rate Swap Agreements (Details 2) (Derivatives designated as cash flow hedges, Interest rate hedges, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivatives designated as cash flow hedges | Interest rate hedges
Effect of derivative instruments on results of operations
Gain (Loss) Recognized in Other Comprehensive Income (Loss) on Derivatives	$ 216	$ (1,318)
Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss)	$ (1,068)	$ (1,260)