Derivatives (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Series F Preferred Stock [Member]	Dec. 31, 2011 Series F Preferred Stock [Member]	Oct. 31, 2008 Series F Preferred Stock [Member]
Derivatives (Textual) [Abstract]
Minimum fixed coupon rate of preferred stock					2.375%
Number of years of U.S treasury rate one					30 years
Number of years of U.S treasury rate two					10 years
LIBOR rate					3 month LIBOR
New coupon rate of preferred stock					5.705%
Notional value of interest rate swap agreement							$ 50,000
Treasury Rate					5.2175%
Outstanding settlement payment due on Series F Agreement					247	280
Derivatives (Additional Textual) [Abstract]
Unrealized mark to market loss on interest rate protection agreement	429	232	305	188
Settlement payments of mark to market gains or losses	247	89	539	188
Amortization to be reclassified from OCI into Income			$ 2,369
Number of years of long dated treasuries			30 years