RENTAL PROPERTIES (Details 3) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended	3 Months Ended	0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 15, 2013 item	May 31, 2013	Jun. 30, 2013	Dec. 20, 2013
RENTAL PROPERTIES
Net proceeds from sale of real estate		$ 2,138,978
Amount of sale proceeds transferred to Investment Property					2,100,000
Effective interest rate (as a percent)	5.33%
Interest paid	8,791,000	8,062,000	7,776,000
Hamilton Green
RENTAL PROPERTIES
Number of units				193
Purchase price of real estate properties				62,500,000
Purchase price allocated to the value of the in-place leases				1,656,000
Purchase price allocated to the value of the tenant relationships				96,000
Amortization period of value of the in-place leases				12 months
Amortization period of value of the tenant relationships				36 months
Short term finance for real estate properties				40,000,000
Proceeds from sale of discontinued operations				2,100,000
Closing costs associated with financing				38,000
Nashoba Apartments in Acton, Massachusetts
RENTAL PROPERTIES
Sales price of real estate properties					4,300,000	4,300,000
Gain on sale of property					3,679,000
Mortgages payable
RENTAL PROPERTIES
Effective interest rate (as a percent)	4.91%
Mortgages payable | Hamilton Green
RENTAL PROPERTIES
Amount of new loan							38,500,000
Interest rate (as a percent)							4.67%
Term of debt							15 years
Amount of mortgage paid off							40,000,000
Closing costs associated with financing							346,000
Period for which the entity is required to make interest only payments							2 years
Amortization period of debt							30 years
Additional capital required for refinancing							$ 1,846,000