RENTAL PROPERTIES (Details)		6 Months Ended
	Jan. 18, 2023 USD ($)	Jun. 30, 2023 property	Jun. 30, 2023 item	Jun. 30, 2023 ft²	Jun. 30, 2023	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 12, 2022 ft²	Jun. 30, 2022 property
RENTAL PROPERTIES
Number of commercial shopping centers | item			2
Rental properties
Total fixed assets						$ 414,543,333	$ 400,703,910
Less: Accumulated depreciation						(167,092,493)	(159,627,479)
Total fixed assets, net						247,450,840	241,076,431
Land, improvements and parking lots
Rental properties
Total fixed assets						90,857,007	87,405,897
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						263,076,029	256,035,191
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						15,029,029	14,347,212
Kitchen cabinets | Minimum
Rental properties
Useful Life		5 years
Kitchen cabinets | Maximum
Rental properties
Useful Life		10 years
Carpets
Rental properties
Total fixed assets						13,035,304	12,047,573
Carpets | Minimum
Rental properties
Useful Life		5 years
Carpets | Maximum
Rental properties
Useful Life		10 years
Air conditioning
Rental properties
Total fixed assets						501,697	501,697
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						553,140	553,140
Laundry equipment | Minimum
Rental properties
Useful Life		5 years
Laundry equipment | Maximum
Rental properties
Useful Life		7 years
Elevators
Rental properties
Total fixed assets						1,885,265	1,885,265
Elevators | Minimum
Rental properties
Useful Life		20 years
Elevators | Maximum
Rental properties
Useful Life		40 years
Swimming pools
Rental properties
Total fixed assets						1,090,604	1,090,604
Swimming pools | Minimum
Rental properties
Useful Life		10 years
Swimming pools | Maximum
Rental properties
Useful Life		30 years
Equipment
Rental properties
Total fixed assets						19,418,136	18,716,758
Equipment | Minimum
Rental properties
Useful Life		5 years
Equipment | Maximum
Rental properties
Useful Life		30 years
Motor vehicles
Rental properties
Total fixed assets						232,954	171,519
Motor vehicles | Maximum
Rental properties
Useful Life		5 years
Fences
Rental properties
Total fixed assets						46,872	46,872
Fences | Minimum
Rental properties
Useful Life		5 years
Fences | Maximum
Rental properties
Useful Life		15 years
Furniture and fixtures
Rental properties
Total fixed assets						$ 8,817,296	$ 7,902,182
Furniture and fixtures | Minimum
Rental properties
Useful Life		5 years
Furniture and fixtures | Maximum
Rental properties
Useful Life		7 years
Wholly owned properties
RENTAL PROPERTIES
Number of properties | property		30
Investment Properties
RENTAL PROPERTIES
Number of units | property		690							865
NERA 40%
RENTAL PROPERTIES
Ownership interest (as a percent)					40.00%				40.00%
NERA 50%
RENTAL PROPERTIES
Ownership interest (as a percent)					50.00%				50.00%
Residential and mixed-use properties | Wholly owned properties
RENTAL PROPERTIES
Number of units | item			2,892
Number of properties | property		25
Residential and mixed-use properties | Partially owned properties
RENTAL PROPERTIES
Number of units		688	688
Rental properties
Area of property (in square feet) | ft²				12,500
Residential and mixed-use properties | Investment Properties | Partially owned properties
RENTAL PROPERTIES
Number of properties | item			7
Residential and mixed-use properties | Limited Partnerships | Partially owned properties
RENTAL PROPERTIES
Number of properties | item			7
Residential and mixed-use properties | NERA 40% | Partially owned properties | Minimum
RENTAL PROPERTIES
Ownership interest (as a percent)					40.00%
Residential and mixed-use properties | NERA 50% | Partially owned properties | Maximum
RENTAL PROPERTIES
Ownership interest (as a percent)					50.00%
Condominium | Wholly owned properties
RENTAL PROPERTIES
Number of units | item			19
Number of properties | property		1
Commercial | Property located at 659 Worcester Road, Framingham, MA.
Rental properties
Purchase price	$ 10,151,000
Closing costs	$ 59,000
Amortization period	12 months
Commercial | Property located at 659 Worcester Road, Framingham, MA. | Leases, Acquired-in-Place [Member]
Rental properties
Purchase price	$ 585,000
Commercial | Property located at 659 Worcester Road, Framingham, MA. | Customer Relationships [Member]
Rental properties
Purchase price	$ 378,000
Commercial | Purchase and sale agreement | Property located at 659 Worcester Road, Framingham, MA.
Rental properties
Area of property (in square feet) | ft²								20,700
Commercial | Minimum | Property located at 659 Worcester Road, Framingham, MA. | Leases, Acquired-in-Place [Member]
Rental properties
Amortization period	20 months
Commercial | Maximum | Property located at 659 Worcester Road, Framingham, MA. | Customer Relationships [Member]
Rental properties
Amortization period	156 months
Commercial | Wholly owned properties
RENTAL PROPERTIES
Number of properties | property		5
Rental properties
Area of property (in square feet) | ft²				128,635
Commercial | Investment Properties
RENTAL PROPERTIES
Number of units | property		3							3