RENTAL PROPERTIES - Real Estate (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	$ 408,605,376
Initial Cost to Partnerships
Land	94,571,556
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	75,839,727
Gross Amount at Which Carried at Close of Period
Land	94,728,084
Building Improvements	366,681,404
Totals	461,409,491	$ 440,496,897	$ 400,703,910	$ 400,588,242
Accumulated Depreciation	182,892,842	$ 170,691,951	$ 159,627,479	$ 149,233,040
Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 290,841,677
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)	$ 33,145,648
Initial Cost to Partnerships
Land	2,112,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	10,131,924
Gross Amount at Which Carried at Close of Period
Land	2,268,528
Building Improvements	18,725,033
Totals	20,993,561
Accumulated Depreciation	$ 16,208,085
Estimated useful lives	3 years
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	992,711
Gross Amount at Which Carried at Close of Period
Land	684,000
Building Improvements	4,108,711
Totals	4,792,711
Accumulated Depreciation	$ 3,123,514
Estimated useful lives	3 years
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	1,706,318
Gross Amount at Which Carried at Close of Period
Land	177,610
Building Improvements	3,184,677
Totals	3,362,287
Accumulated Depreciation	$ 2,570,878
Estimated useful lives	3 years
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	966,750
Gross Amount at Which Carried at Close of Period
Land	342,000
Building Improvements	2,334,419
Totals	2,676,419
Accumulated Depreciation	$ 2,040,060
Estimated useful lives	3 years
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	7,376,561
Gross Amount at Which Carried at Close of Period
Land	1,410,000
Building Improvements	13,041,377
Totals	14,451,377
Accumulated Depreciation	$ 8,213,836
Estimated useful lives	3 years
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	3,160,364
Gross Amount at Which Carried at Close of Period
Land	91,400
Building Improvements	3,900,724
Totals	3,992,124
Accumulated Depreciation	$ 1,780,436
Estimated useful lives	3 years
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)	3,629,770
Initial Cost to Partnerships
Land	1,341,737
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	214,659
Gross Amount at Which Carried at Close of Period
Land	1,341,737
Building Improvements	8,672,156
Totals	10,013,893
Accumulated Depreciation	$ 4,722,614
Estimated useful lives	3 years
Hamilton Battle Green LLC Residential Apartments Lexington, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 8,457,497
Hamilton Cypress LLC Commercial-1031 Exchange Brookline, Massachusetts
Initial Cost to Partnerships
Land	2,362,795
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	396,087
Gross Amount at Which Carried at Close of Period
Land	2,362,795
Building Improvements	5,009,873
Totals	7,372,668
Accumulated Depreciation	$ 2,114,943
Estimated useful lives	3 years
Hamilton Cypress LLC Commercial-1031 Exchange Brookline, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 4,613,786
Hamilton Green Apartments, LLC Residential Apartments Andover, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	31,336,828
Initial Cost to Partnerships
Land	15,413,457
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	(7,956,599)
Gross Amount at Which Carried at Close of Period
Land	15,413,457
Building Improvements	37,478,718
Totals	52,892,174
Accumulated Depreciation	$ 18,445,291
Estimated useful lives	3 years
Hamilton Green Apartments, LLC Residential Apartments Andover, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 45,435,317
Hamilton Highlands, LLC Residential Apartments Needham, Massachsetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	18,970,055
Initial Cost to Partnerships
Land	7,973,547
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	(2,314,505)
Gross Amount at Which Carried at Close of Period
Land	7,973,547
Building Improvements	23,789,557
Totals	31,763,105
Accumulated Depreciation	$ 7,184,396
Estimated useful lives	3 years
Hamilton Highlands, LLC Residential Apartments Needham, Massachsetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 26,104,062
Hamilton Linewt LLC Commercial 1031 Exchange Newton, Massachusetts
Initial Cost to Partnerships
Land	984,522
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	225,807
Gross Amount at Which Carried at Close of Period
Land	984,522
Building Improvements	2,777,454
Totals	3,761,976
Accumulated Depreciation	$ 1,205,077
Estimated useful lives	3 years
Hamilton Linewt LLC Commercial 1031 Exchange Newton, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 2,551,647
Hamilton Oaks Associates LLC Residential Apartments Brockton, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	26,666,000
Initial Cost to Partnerships
Land	2,245,236
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	7,290,908
Gross Amount at Which Carried at Close of Period
Land	2,245,236
Building Improvements	19,545,672
Totals	21,790,908
Accumulated Depreciation	$ 14,856,258
Estimated useful lives	3 years
Hamilton Oaks Associates LLC Residential Apartments Brockton, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 12,254,764
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	470,131
Gross Amount at Which Carried at Close of Period
Land	156,000
Building Improvements	1,104,216
Totals	1,260,216
Accumulated Depreciation	$ 901,683
Estimated useful lives	3 years
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	1,916,402
Gross Amount at Which Carried at Close of Period
Land	385,000
Building Improvements	3,456,402
Totals	3,841,402
Accumulated Depreciation	$ 2,814,097
Estimated useful lives	3 years
Linhart L.P. Residential/Commercial Newton, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 1,540,000
Mill Street Gardens, LLC Residential Apartments Woburn, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	31,000,000
Initial Cost to Partnerships
Land	12,689,705
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	3,132,843
Gross Amount at Which Carried at Close of Period
Land	12,689,705
Building Improvements	43,810,528
Totals	56,500,232
Accumulated Depreciation	$ 14,596,138
Estimated useful lives	3 years
Mill Street Gardens, LLC Residential Apartments Woburn, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 40,677,685
Mill Street Development, Woburn, Massachusetts
Initial Cost to Partnerships
Land	1,376,031
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	14,631,473
Gross Amount at Which Carried at Close of Period
Land	1,376,031
Building Improvements	15,755,442
Totals	$ 17,131,474
Estimated useful lives	3 years
Mill Street Development, Woburn, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 1,123,969
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	1,516,015
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,929,626
Gross Amount at Which Carried at Close of Period
Land	1,516,015
Building Improvements	7,627,091
Totals	9,143,105
Accumulated Depreciation	$ 5,738,167
Estimated useful lives	3 years
NERA Dean St. Associates LLC Residential Apartments Norwood, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 5,697,465
North Beacon 140 L.P. Residential Apartments Boston, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	12,683,000
Initial Cost to Partnerships
Land	1,200,620
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	2,379,430
Gross Amount at Which Carried at Close of Period
Land	1,200,620
Building Improvements	5,876,823
Totals	7,077,444
Accumulated Depreciation	$ 5,732,234
Estimated useful lives	3 years
North Beacon 140 L.P. Residential Apartments Boston, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 3,497,393
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	77,454
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,320,693
Gross Amount at Which Carried at Close of Period
Land	77,454
Building Improvements	2,167,743
Totals	2,245,198
Accumulated Depreciation	$ 1,616,847
Estimated useful lives	3 years
Olde English Apartments L.P. Residential Apartments Lowell, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 847,050
Redwood Hills L.P. Residential Apartments Worcester, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	17,105,000
Initial Cost to Partnerships
Land	1,278,412
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	6,620,483
Gross Amount at Which Carried at Close of Period
Land	1,278,412
Building Improvements	11,352,675
Totals	12,631,087
Accumulated Depreciation	$ 8,539,907
Estimated useful lives	3 years
Redwood Hills L.P. Residential Apartments Worcester, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 4,732,192
Residences at Captain Parkers LLC Residential Apartments Lexington, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	20,750,000
Initial Cost to Partnerships
Land	7,755,055
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	401,218
Gross Amount at Which Carried at Close of Period
Land	7,755,055
Building Improvements	23,848,093
Totals	31,603,148
Accumulated Depreciation	$ 8,855,972
Estimated useful lives	3 years
Residences at Captain Parkers LLC Residential Apartments Lexington, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 23,446,875
River Drive L.P. Residential Apartments Danvers, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	9,543,000
Initial Cost to Partnerships
Land	109,697
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	2,563,250
Gross Amount at Which Carried at Close of Period
Land	109,697
Building Improvements	3,113,855
Totals	3,223,552
Accumulated Depreciation	$ 1,299,071
Estimated useful lives	3 years
River Drive L.P. Residential Apartments Danvers, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 550,605
Riverside Apartments Condominium Units Watertown Massachustts
Initial Cost to Partnerships
Land	23,346
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	164,214
Gross Amount at Which Carried at Close of Period
Land	23,346
Building Improvements	355,021
Totals	378,368
Accumulated Depreciation	$ 315,084
Estimated useful lives	3 years
Riverside Apartments Condominium Units Watertown Massachustts | 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	686,148
Gross Amount at Which Carried at Close of Period
Land	4,686,728
Building Improvements	19,433,059
Totals	24,119,787
Accumulated Depreciation	$ 14,213,187
Estimated useful lives	3 years
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)	5,935,643
Initial Cost to Partnerships
Land	3,280,000
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	521,762
Gross Amount at Which Carried at Close of Period
Land	3,280,000
Building Improvements	5,441,762
Totals	8,721,762
Accumulated Depreciation	$ 4,322,108
Estimated useful lives	3 years
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	1,719,517
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	3,588,269
Gross Amount at Which Carried at Close of Period
Land	1,719,517
Building Improvements	10,769,253
Totals	12,488,769
Accumulated Depreciation	$ 8,900,504
Estimated useful lives	3 years
WCB Associates LLC Residential Apartments Brockton, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 7,180,984
Westgate Apartments Burlington LLC Residential Apartments Burlington, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	4,494,000
Initial Cost to Partnerships
Land	191,275
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	335,604
Gross Amount at Which Carried at Close of Period
Land	191,275
Building Improvements	4,667,981
Totals	4,859,256
Accumulated Depreciation	$ 3,582,655
Estimated useful lives	3 years
Westgate Apartments Burlington LLC Residential Apartments Burlington, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 4,332,377
Westgate Apartments LLC Residential Apartments Woburn, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	38,475,000
Initial Cost to Partnerships
Land	521,495
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	7,264,671
Gross Amount at Which Carried at Close of Period
Land	521,495
Building Improvements	9,629,112
Totals	10,150,607
Accumulated Depreciation	$ 6,686,894
Estimated useful lives	3 years
Westgate Apartments LLC Residential Apartments Woburn, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 2,364,441
Woodland Park Apartments LLC Residential Apartments Newton Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	21,378,432
Initial Cost to Partnerships
Land	11,754,450
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	(3,242,049)
Gross Amount at Which Carried at Close of Period
Land	11,754,450
Building Improvements	29,992,829
Totals	41,747,280
Accumulated Depreciation	$ 9,638,270
Estimated useful lives	3 years
Woodland Park Apartments LLC Residential Apartments Newton Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 33,234,878
653 Worcester Rd, Framingham, Massachusetts
Initial Cost to Partnerships
Land	3,415,051
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	1,218,488
Gross Amount at Which Carried at Close of Period
Land	3,415,051
Building Improvements	5,715,337
Totals	9,130,389
Accumulated Depreciation	$ 883,250
Estimated useful lives	3 years
653 Worcester Rd, Framingham, Massachusetts | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 4,496,849
Shawmut Place LLC Boston, Massachuseyys
Initial Cost to Partnerships
Land	7,297,401
Cost Capitalized Subsequent to Acquisition
Improvements, Net of retirements	7,746,086
Gross Amount at Which Carried at Close of Period
Land	7,297,401
Building Improvements	19,995,811
Totals	27,293,212
Accumulated Depreciation	$ 1,791,386
Estimated useful lives	3 years
Shawmut Place LLC Boston, Massachuseyys | Buildings and improvements
Initial Cost to Partnerships
Building Improvements	$ 12,249,725