ACQUISITIONS AND DISPOSITIONS (Details) (USD $)	1 Months Ended	3 Months Ended	1 Months Ended				1 Months Ended		3 Months Ended	9 Months Ended		1 Months Ended	3 Months Ended	9 Months Ended
	Aug. 31, 2012	Sep. 30, 2012 item	May 31, 2012 Millennium Woodlands Phase II, LLC. item	Aug. 31, 2012 70 Columbia Corporate Center sqft	Sep. 30, 2012 70 Columbia Corporate Center	Aug. 15, 2012 70 Columbia Corporate Center sqft	Jul. 31, 2011 The Woodlands	Jun. 30, 2011 The Woodlands	Sep. 30, 2011 The Woodlands	Sep. 30, 2011 The Woodlands	Jul. 02, 2011 The Woodlands	May 31, 2012 Millennium Waterway Apartments	Sep. 30, 2012 Millennium Waterway Apartments	Sep. 30, 2012 Millennium Waterway Apartments
Acquisitions
Area of real estate property acquired (in square foot)						169,590
Purchase price						$ 17,500,000					$ 117,500,000
Interest rate (as a percent)					4.25%								3.75%	3.75%
Percentage of appreciation in the market value of building				30.00%
Percentage of building leased at closing						23.70%
Area of building leased				76,308
Percentage of occupancy after lease is executed						68.70%
Amount deposited in escrow account				5,000,000
Percentage of cumulative preferred return after debt service on amount invested in property				10.00%
Original contributed equity						5,000,000
Percentage distribution of excess proceeds after repayment of outstanding debt and preferred return	70.00%			30.00%
Total assets consolidated into financial statements at fair value as of the acquisition date												78,600,000
Total liabilities consolidated into financial statements at fair value as of the acquisition date												56,400,000
Number of Units Acquired in Real Estate Property		393
Portion of refinanced mortgage proceeds used to acquire partner's interest												6,900,000
Non-recourse mortgage assumed												55,600,000
Term of debt instrument												10 years
Ownership interest (as a percent)												100.00%
Revenues and net losses included in the condensed consolidated statement of operations since the acquisition date
Revenues									40,300,000	40,300,000			1,900,000	2,500,000
Net earnings									7,900,000				600,000	900,000
Impact of increase in cost of sales on net loss									8,600,000
Number of units in Class A multi-family unit in The Woodlands Town Center to be constructed			314
Percentage of economic interest acquired							47.50%
Percentage of legal interest acquired											57.50%
After-tax loss on the remeasurement relating to existing economic interest								3,900,000
Existing economic interest (as a percent)								52.50%
Net book value of existing economic interest								134,800,000
Pro Forma Information
Total revenues										276,240,000
Net income (loss) attributable to common shareholders										$ 112,393,000