SUBSEQUENT EVENTS (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended				1 Months Ended
	Feb. 28, 2012 Chief Executive Officer [Member] Issuance of Equity Related to Share-based Compensation Plan [Member]	Feb. 28, 2012 Chief Executive Officer [Member] Sale of Equity Shares by Executive Officer [Member]	Jan. 31, 2012 1520 North Milwaukee Avenue [Member] Chicago Illinois [Member] Acquisition [Member] sqft	Feb. 28, 2012 640 Broadway [Member] New York New York [Member] Fund III [Member] Acquisition [Member]	Feb. 28, 2012 Single Tenant Property [Member] Cambridge Massachusetts [Member] Acquisition [Member] sqft	Apr. 30, 2011 Opportunity Funds [Member] Chicago Illinois [Member] Fund III [Member] sqft	Feb. 28, 2012 Opportunity Funds [Member] 640 Broadway [Member] New York New York [Member] Fund III [Member] Acquisition [Member] sqft	Jan. 31, 2012 Common Stock [Member] Maximum [Member] Issuance of Equity [Member]
Subsequent Event [Line Items]
Common Stock, Reserved for Future Issuance, Value, At The Market Equity Program								$ 75.0
Square Footage of Real Estate Property (in feet)			3,100		40,000	105,000	45,700
Business Acquisition, Cost of Acquired Entity, Purchase Price			3.8	32.5	19.2	31.6
Business Acquisition, Debt Assumption					$ 7.0
Stock Issued During Period, Shares, Conversion of Units (in shares)	150,000
Number of Shares of Common Stock Sold by Executive (in shares)		75,000