Components of Rental Income and Expense (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Components of Rental Income and Expense (Textual) [Abstract]
Recognition of straight-line rents	$ 2.0	$ 1.2	$ 4.0	$ 1.3
Recognition of amortization of above and below market leases	$ (0.2)	$ (0.4)	$ (0.7)	$ (0.8)