Subsequent Events (Details Textuals) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2011 Property Tenants Year sqft	Sep. 30, 2010	Oct. 28, 2011 sqft
Subsequent Events (Textuals) [Abstract]
Number of office properties sold	2
Aggregate square footage of properties sold			206,243
Aggregate sale price of properties sold		$ 22.8
Five Greentree Centre [Member]
Subsequent Event [Line Items]
Percentage Occupancy of Properties Sold			96.10%
Lake Center Two Member
Subsequent Event [Line Items]
Percentage Occupancy of Properties Sold			47.80%