Deferred Costs (Details Textuals) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Deferred Costs (Textuals) [Abstract]
Capitalized internal direct leasing costs	$ 1.7	$ 1.4	$ 5.4	$ 4.7