RENTAL PROPERTIES - Real Estate Detail (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	$ 414,125,232
Initial Cost to Partnerships
Land	75,124,253
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	42,593,173
Gross Amount at Which Carried at Close of Period
Land	75,280,781
Building Improvements	325,423,127
Totals	400,703,911	$ 400,588,242	$ 398,629,793	$ 398,554,000
Accumulated Depreciation	159,627,479	$ 149,233,040	$ 134,019,906	$ 120,190,012
Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 282,829,954
Buildings and improvements | Minimum
Gross Amount at Which Carried at Close of Period
Estimated useful lives	10 years
Buildings and improvements | Maximum
Gross Amount at Which Carried at Close of Period
Estimated useful lives	40 years
Other Categories of Assets | Minimum
Gross Amount at Which Carried at Close of Period
Estimated useful lives	5 years
Other Categories of Assets | Maximum
Gross Amount at Which Carried at Close of Period
Estimated useful lives	15 years
Boylston Downtown L.P. Residential Apartments Boston, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	$ 35,002,712
Initial Cost to Partnerships
Land	2,112,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	10,017,430
Gross Amount at Which Carried at Close of Period
Land	2,268,528
Building Improvements	18,610,539
Totals	20,879,067
Accumulated Depreciation	15,677,522
Boylston Downtown L.P. Residential Apartments Boston, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	8,593,109
Brookside Associates LLC Residential Apartments Woburn, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	6,175,000
Initial Cost to Partnerships
Land	684,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	474,538
Gross Amount at Which Carried at Close of Period
Land	684,000
Building Improvements	3,590,538
Totals	4,274,538
Accumulated Depreciation	2,809,689
Brookside Associates LLC Residential Apartments Woburn, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	3,116,000
Clovelly Apartments L.P. Residential Apartments Nashua, New Hampshire
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	11,214,000
Initial Cost to Partnerships
Land	177,610
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,595,610
Gross Amount at Which Carried at Close of Period
Land	177,610
Building Improvements	3,073,969
Totals	3,251,579
Accumulated Depreciation	2,484,683
Clovelly Apartments L.P. Residential Apartments Nashua, New Hampshire | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	1,478,359
Commonwealth 1137 L.P. Residential Apartments Boston, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	5,440,000
Initial Cost to Partnerships
Land	342,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	987,302
Gross Amount at Which Carried at Close of Period
Land	342,000
Building Improvements	2,354,971
Totals	2,696,971
Accumulated Depreciation	2,090,340
Commonwealth 1137 L.P. Residential Apartments Boston, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	1,367,669
Commonwealth 1144 L.P. Residential Apartments Boston, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	32,325,000
Initial Cost to Partnerships
Land	1,410,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	4,757,194
Gross Amount at Which Carried at Close of Period
Land	1,410,000
Building Improvements	10,422,010
Totals	11,832,010
Accumulated Depreciation	7,974,356
Commonwealth 1144 L.P. Residential Apartments Boston, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	5,664,816
Executive Apartments L.P. Residential Apartments Framingham, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	8,190,000
Initial Cost to Partnerships
Land	91,400
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,446,236
Gross Amount at Which Carried at Close of Period
Land	91,400
Building Improvements	2,186,596
Totals	2,277,996
Accumulated Depreciation	1,519,164
Executive Apartments L.P. Residential Apartments Framingham, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	740,360
Hamilton Battle Green LLC Residential Apartments Lexington, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	3,896,953
Initial Cost to Partnerships
Land	1,341,737
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	135,440
Gross Amount at Which Carried at Close of Period
Land	1,341,737
Building Improvements	8,592,937
Totals	9,934,674
Accumulated Depreciation	4,010,934
Hamilton Battle Green LLC Residential Apartments Lexington, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	8,457,497
Hamilton Cypress LLC Commercial-1031Exchange Brookline, Massachusetts
Initial Cost to Partnerships
Land	2,362,596
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	19,392
Gross Amount at Which Carried at Close of Period
Land	2,362,596
Building Improvements	4,633,377
Totals	6,995,973
Accumulated Depreciation	1,854,782
Hamilton Cypress LLC Commercial-1031Exchange Brookline, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	4,613,985
Hamilton Green Apartments Residential Apartments Andover, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	33,005,333
Initial Cost to Partnerships
Land	16,054,336
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	(8,244,684)
Gross Amount at Which Carried at Close of Period
Land	16,054,336
Building Improvements	36,549,754
Totals	52,604,090
Accumulated Depreciation	15,240,165
Hamilton Green Apartments Residential Apartments Andover, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	44,794,438
Hamilton Highlands LLC Residential Needham Massachusetts [Member]
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	19,870,995
Initial Cost to Partnerships
Land	6,815,522
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	843,216
Gross Amount at Which Carried at Close of Period
Land	6,815,522
Building Improvements	28,105,303
Totals	34,920,825
Accumulated Depreciation	8,228,990
Hamilton Highlands LLC Residential Needham Massachusetts [Member] | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	27,262,087
Hamilton Linewt LLC Commercial-1031 Exchange Newton, Massachusetts
Initial Cost to Partnerships
Land	884,042
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	134,614
Gross Amount at Which Carried at Close of Period
Land	884,042
Building Improvements	2,786,741
Totals	3,670,783
Accumulated Depreciation	1,060,266
Hamilton Linewt LLC Commercial-1031 Exchange Newton, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	2,652,127
Hamilton Oaks Associates LLC Residential Apartments Brockton, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	26,666,000
Initial Cost to Partnerships
Land	2,175,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	5,013,492
Gross Amount at Which Carried at Close of Period
Land	2,175,000
Building Improvements	17,338,492
Totals	19,513,492
Accumulated Depreciation	13,158,563
Hamilton Oaks Associates LLC Residential Apartments Brockton, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	12,325,000
Highland Street Apartments, L.P. Residential Apartments Lowell, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	3,960,000
Initial Cost to Partnerships
Land	156,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	401,763
Gross Amount at Which Carried at Close of Period
Land	156,000
Building Improvements	1,035,848
Totals	1,191,848
Accumulated Depreciation	811,257
Highland Street Apartments, L.P. Residential Apartments Lowell, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	634,085
Linhart L.P. Residential/Commercial Newton, Massachusetts
Initial Cost to Partnerships
Land	385,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,855,862
Gross Amount at Which Carried at Close of Period
Land	385,000
Building Improvements	3,395,862
Totals	3,780,862
Accumulated Depreciation	2,867,700
Linhart L.P. Residential/Commercial Newton, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	1,540,000
Mill Street Gardens Residential Apartments Woburn Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	31,000,000
Initial Cost to Partnerships
Land	9,798,478
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	2,835,600
Gross Amount at Which Carried at Close of Period
Land	9,798,478
Building Improvements	46,404,512
Totals	56,202,990
Accumulated Depreciation	8,739,788
Mill Street Gardens Residential Apartments Woburn Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	43,568,912
Mill Street Development Woburn Massachusetts
Initial Cost to Partnerships
Land	1,375,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	268,580
Gross Amount at Which Carried at Close of Period
Land	1,375,000
Building Improvements	1,393,580
Totals	2,768,580
Accumulated Depreciation	124,030
Mill Street Development Woburn Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	1,125,000
NERA Dean St. Associates LLC Residential Apartments Norwood, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	10,322,000
Initial Cost to Partnerships
Land	1,512,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,319,949
Gross Amount at Which Carried at Close of Period
Land	1,512,000
Building Improvements	7,021,429
Totals	8,533,429
Accumulated Depreciation	5,075,486
NERA Dean St. Associates LLC Residential Apartments Norwood, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	5,701,480
North Beacon 140 L.P. Residential Units Boston, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	12,683,000
Initial Cost to Partnerships
Land	936,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	2,426,416
Gross Amount at Which Carried at Close of Period
Land	936,000
Building Improvements	6,188,429
Totals	7,124,429
Accumulated Depreciation	5,610,496
North Beacon 140 L.P. Residential Units Boston, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	3,762,013
Olde English Apartments L.P. Residential Apartments Lowell, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	9,608,000
Initial Cost to Partnerships
Land	46,181
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,264,410
Gross Amount at Which Carried at Close of Period
Land	46,181
Building Improvements	2,142,733
Totals	2,188,914
Accumulated Depreciation	1,470,935
Olde English Apartments L.P. Residential Apartments Lowell, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	878,323
Redwood Hills L.P. Residential Units Worcester, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	17,105,000
Initial Cost to Partnerships
Land	1,200,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	5,384,946
Gross Amount at Which Carried at Close of Period
Land	1,200,000
Building Improvements	10,195,550
Totals	11,395,550
Accumulated Depreciation	7,768,753
Redwood Hills L.P. Residential Units Worcester, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	4,810,604
Residences at CaptainParkers LLC Residential Apartments Lexington, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	20,750,000
Initial Cost to Partnerships
Land	6,247,153
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	77,023
Gross Amount at Which Carried at Close of Period
Land	6,247,153
Building Improvements	25,031,800
Totals	31,278,953
Accumulated Depreciation	7,204,090
Residences at CaptainParkers LLC Residential Apartments Lexington, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	24,954,777
River Drive L.P. Residential Apartments Danvers, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	9,543,000
Initial Cost to Partnerships
Land	72,525
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,355,005
Gross Amount at Which Carried at Close of Period
Land	72,525
Building Improvements	1,942,782
Totals	2,015,307
Accumulated Depreciation	1,095,614
River Drive L.P. Residential Apartments Danvers, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	587,777
Riverside Apartments Condominium Units Massachusetts
Initial Cost to Partnerships
Land	23,346
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	146,281
Gross Amount at Which Carried at Close of Period
Land	23,346
Building Improvements	337,088
Totals	360,434
Accumulated Depreciation	284,401
Riverside Apartments Condominium Units Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	190,807
School St Assoc LLC Residential Apartments Framingham, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	26,993,000
Initial Cost to Partnerships
Land	4,686,728
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	(214,784)
Gross Amount at Which Carried at Close of Period
Land	4,686,728
Building Improvements	18,532,127
Totals	23,218,855
Accumulated Depreciation	12,635,977
School St Assoc LLC Residential Apartments Framingham, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	18,746,911
WRF Associates LLC Strip Mall Framingham, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	5,954,546
Initial Cost to Partnerships
Land	3,280,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	81,477
Gross Amount at Which Carried at Close of Period
Land	3,280,000
Building Improvements	5,001,477
Totals	8,281,477
Accumulated Depreciation	3,906,943
WRF Associates LLC Strip Mall Framingham, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	4,920,000
WCB Associates LLC Residential Apartments Brockton, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	19,266,000
Initial Cost to Partnerships
Land	1,335,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	2,978,648
Gross Amount at Which Carried at Close of Period
Land	1,335,000
Building Improvements	10,544,149
Totals	11,879,149
Accumulated Depreciation	8,059,088
WCB Associates LLC Residential Apartments Brockton, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	7,565,501
Westgate Apartments Residential Units Burlington Massachusetts Member
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	4,494,000
Initial Cost to Partnerships
Land	44,965
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	304,524
Gross Amount at Which Carried at Close of Period
Land	44,965
Building Improvements	4,783,211
Totals	4,828,176
Accumulated Depreciation	3,221,610
Westgate Apartments Residential Units Burlington Massachusetts Member | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	4,478,687
Westgate Apartments LLC Residential Apartments Woburn, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	38,475,000
Initial Cost to Partnerships
Land	461,300
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	6,284,273
Gross Amount at Which Carried at Close of Period
Land	461,300
Building Improvements	8,708,909
Totals	9,170,209
Accumulated Depreciation	5,933,042
Westgate Apartments LLC Residential Apartments Woburn, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	2,424,636
Woodland Park Apartments LLC Newton Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	22,185,693
Initial Cost to Partnerships
Land	9,114,334
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	(1,356,580)
Gross Amount at Which Carried at Close of Period
Land	9,114,334
Building Improvements	34,518,414
Totals	43,632,748
Accumulated Depreciation	8,708,815
Woodland Park Apartments LLC Newton Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 35,874,994