RENTAL PROPERTIES (Details)	9 Months Ended
	Sep. 30, 2016 USD ($) property item	Dec. 31, 2015 USD ($)	Sep. 30, 2015 property	Sep. 18, 2015 item
Rental properties
Total fixed assets	$ 264,172,757	$ 261,276,898
Less: Accumulated depreciation	(93,320,604)	(84,579,584)
Total fixed assets, net	170,852,153	176,697,314
Land, improvements and parking lots
Rental properties
Total fixed assets	$ 52,610,465	52,852,877
Land, improvements and parking lots | Minimum
Rental properties
Useful Life	15 years
Land, improvements and parking lots | Maximum
Rental properties
Useful Life	40 years
Buildings and improvements
Rental properties
Total fixed assets	$ 173,161,839	172,277,299
Buildings and improvements | Minimum
Rental properties
Useful Life	15 years
Buildings and improvements | Maximum
Rental properties
Useful Life	40 years
Kitchen cabinets
Rental properties
Total fixed assets	$ 8,919,826	8,493,696
Kitchen cabinets | Minimum
Rental properties
Useful Life	5 years
Kitchen cabinets | Maximum
Rental properties
Useful Life	10 years
Carpets
Rental properties
Total fixed assets	$ 8,039,112	7,361,966
Carpets | Minimum
Rental properties
Useful Life	5 years
Carpets | Maximum
Rental properties
Useful Life	10 years
Air conditioning
Rental properties
Total fixed assets	$ 718,531	718,531
Air conditioning | Minimum
Rental properties
Useful Life	5 years
Air conditioning | Maximum
Rental properties
Useful Life	10 years
Laundry equipment
Rental properties
Total fixed assets	$ 244,771	244,771
Laundry equipment | Minimum
Rental properties
Useful Life	5 years
Laundry equipment | Maximum
Rental properties
Useful Life	7 years
Elevators
Rental properties
Total fixed assets	$ 1,139,296	1,139,296
Elevators | Minimum
Rental properties
Useful Life	20 years
Elevators | Maximum
Rental properties
Useful Life	40 years
Swimming pools
Rental properties
Total fixed assets	$ 444,629	444,629
Swimming pools | Minimum
Rental properties
Useful Life	10 years
Swimming pools | Maximum
Rental properties
Useful Life	30 years
Equipment
Rental properties
Total fixed assets	$ 10,125,881	9,502,977
Equipment | Minimum
Rental properties
Useful Life	5 years
Equipment | Maximum
Rental properties
Useful Life	7 years
Motor vehicles
Rental properties
Total fixed assets	$ 169,076	130,563
Motor vehicles | Maximum
Rental properties
Useful Life	5 years
Fences
Rental properties
Total fixed assets	$ 42,565	38,115
Fences | Minimum
Rental properties
Useful Life	5 years
Fences | Maximum
Rental properties
Useful Life	15 years
Furniture and fixtures
Rental properties
Total fixed assets	$ 8,339,939	7,855,351
Furniture and fixtures | Minimum
Rental properties
Useful Life	5 years
Furniture and fixtures | Maximum
Rental properties
Useful Life	7 years
Smoke alarms
Rental properties
Total fixed assets	$ 216,827	$ 216,827
Smoke alarms | Minimum
Rental properties
Useful Life	5 years
Smoke alarms | Maximum
Rental properties
Useful Life	7 years
Residences at CaptainParkers LLC Residential Apartments Lexington, Massachusetts
RENTAL PROPERTIES
Number of units | item				94
Wholly owned properties
RENTAL PROPERTIES
Number of properties | item	25
Investment Properties
RENTAL PROPERTIES
Number of units | property	1,033		1,033
Residential and mixed-use properties
RENTAL PROPERTIES
Number of units | item	2,506
Number of properties | item	21
Residential and mixed-use properties | Partially owned properties
RENTAL PROPERTIES
Number of units | item	778
Number of properties | item	9
Residential and mixed-use properties | Partially owned properties | Minimum
RENTAL PROPERTIES
Ownership interest (as a percent)	40.00%
Residential and mixed-use properties | Partially owned properties | Maximum
RENTAL PROPERTIES
Ownership interest (as a percent)	50.00%
Residential and mixed-use properties | Investment Properties | Partially owned properties
RENTAL PROPERTIES
Number of units | property	778
Condominium
RENTAL PROPERTIES
Number of units | item	19
Condominium | Wholly owned properties
RENTAL PROPERTIES
Number of units | item	19
Number of properties | item	1