Deferred Costs (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Deferred Costs (Textuals) [Abstract]
Capitalized internal direct leasing costs	$ 1.4	$ 1.7	$ 2.7	$ 3.2