ACQUISITIONS AND DISPOSITIONS (Details) (USD $)	3 Months Ended	1 Months Ended		3 Months Ended	6 Months Ended		1 Months Ended	3 Months Ended
	Jun. 30, 2012 item	May 31, 2012 Millennium Woodlands Phase II, LLC. item	Jul. 31, 2011 The Woodlands	Jun. 30, 2011 The Woodlands	Jun. 30, 2011 The Woodlands	Jul. 01, 2011 The Woodlands	May 31, 2012 Millennium Waterway Apartments	Jun. 30, 2012 Millennium Waterway Apartments
Acquisitions
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
Interest rate (as a percent)								3.75%
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
Ownership interest (as a percent)							100.00%
Revenues and net losses included in the consolidated statement of operations since the acquisition date
Revenues								600,000
Net income								300,000
Number of units in Class A multi-family unit in The Woodlands Town Center to be constructed		314
Purchase price						117,500,000
Percentage of economic interest acquired			47.50%
Percentage of legal interest acquired						57.50%
Pro Forma Information
Total revenues				95,586,000	185,847,000
Net income (loss) attributable to common shareholders				$ 72,702,000	$ (37,888,000)