Derivative Instruments and Hedging Activities (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Total effect of derivative instruments on other comprehensive income	$ 46	$ (215)	$ 53	$ (220)
Interest Rate Cap [Member]
Total effect of derivative instruments on other comprehensive income	0	(70)	(4)	(74)
Interest Rate Swap [Member]
Total effect of derivative instruments on other comprehensive income	$ 46	$ (145)	$ 57	$ (146)