ACQUISITIONS AND DEVELOPMENT (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended			12 Months Ended
	Dec. 31, 2012 The Apartments at Cobblestone Square item	Dec. 31, 2011 Eleven55 Ripley item	Dec. 31, 2012 Eleven55 Ripley	Dec. 31, 2011 Eleven55 Ripley - 21 story building item	Dec. 31, 2011 Eleven55 Ripley - 5 story building item	Jun. 30, 2012 Courts at Spring Mill Station item	Dec. 31, 2012 Courts at Spring Mill Station	Dec. 31, 2012 Arbor Park of Alexandria item	Dec. 31, 2012 Falkland Chase item	Dec. 31, 2012 Falkland Chase Minimum item	Dec. 31, 2012 Falkland Chase Maximum item
Acquisitions and development
Construction in progress for development, number of buildings	8	2				2
Construction in progress for development, number of stories in each building	4			21	5
Construction in progress for development, number of units	314	379				385
Number of buildings completed and occupied								26
Total construction cost	$ 48,609		$ 62,502				$ 20,739
Average cost per apartment unit (in dollars per unit)	155
Number of projects in redevelopment								1
Number of garden apartments under redevelopment phase								851	450
Number of buildings under redevelopment phase								52
Number of buildings under renovation								5
Number of units under renovation								90
Number of units completed								391
Number of units occupied								290
Construction in progress included in buildings, improvements, equipment or other assets								$ 14,006	$ 4,762
Number of projects in pre-redevelopment									1
Pre-redevelopment construction, number of units										182	1,185