RENTAL PROPERTIES (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Rental Properties
Balance, Beginning	$ 221,454,286	$ 158,624,893	$ 159,123,799
Additions:
Buildings, improvements and other assets	5,604,791	65,349,698	2,360,399
Balance before deductions	227,059,077	223,974,591	161,484,198
Deduct
Write-offs of retired or disposed assets	2,037,131	2,505,787	1,607,830
Rental properties held for sale and/or sold		14,518	1,251,475
Balance, Ending	225,021,946	221,454,286	158,624,893
Accumulated Depreciation
Balance, Beginning	68,549,625	63,651,293	60,199,265
Add:
Depreciation for the year	9,393,368	7,404,120	5,849,083
Total additions	77,942,993	71,055,413	66,048,348
Deduct:
Accumulated depreciation of retired or disposed assets	2,037,131	2,505,788	1,607,830
Accumulated depreciation of rental properties held for sale and/or sold			789,225
Balance, Ending	75,905,862	68,549,625	63,651,293
Encumbrances (First Mortgages)	196,071,540
Initial Cost to Partnerships
Land	41,773,766
Building Improvements	150,044,184
Cost Capitalized Subsequent to Acquisition
Improvements	33,248,189
Gross Amount at Which Carried at Close of Period
Land	41,729,573
Building Improvements	183,292,373
Totals	225,021,946	221,454,286	158,624,893
Accumulated Depreciation	75,905,862	68,549,625	63,651,293
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	39 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
Deduct
Balance, Ending	18,386,522
Deduct:
Balance, Ending	10,220,358
Encumbrances (First Mortgages)	40,000,000
Initial Cost to Partnerships
Land	2,112,000
Building Improvements	8,593,109
Cost Capitalized Subsequent to Acquisition
Improvements	7,681,413
Gross Amount at Which Carried at Close of Period
Land	2,112,000
Building Improvements	16,274,522
Totals	18,386,522
Accumulated Depreciation	10,220,358
Brookside Associates LLC Residential Apartments Woburn, Massachusetts
Deduct
Balance, Ending	4,264,970
Deduct:
Balance, Ending	1,858,026
Encumbrances (First Mortgages)	2,642,649
Initial Cost to Partnerships
Land	684,000
Building Improvements	3,116,000
Cost Capitalized Subsequent to Acquisition
Improvements	464,970
Gross Amount at Which Carried at Close of Period
Land	684,000
Building Improvements	3,580,970
Totals	4,264,970
Accumulated Depreciation	1,858,026
Clovelly Apartments L.P. Residential Apartments Nashua, New Hampshire
Deduct
Balance, Ending	3,317,241
Deduct:
Balance, Ending	2,081,134
Encumbrances (First Mortgages)	4,160,000
Initial Cost to Partnerships
Land	177,610
Building Improvements	1,478,359
Cost Capitalized Subsequent to Acquisition
Improvements	1,661,272
Gross Amount at Which Carried at Close of Period
Land	177,610
Building Improvements	3,139,631
Totals	3,317,241
Accumulated Depreciation	2,081,134
Commonwealth 1137 L.P. Residential Apartments Boston, Massachusetts
Deduct
Balance, Ending	2,893,182
Deduct:
Balance, Ending	1,416,545
Encumbrances (First Mortgages)	3,750,000
Initial Cost to Partnerships
Land	342,000
Building Improvements	1,367,669
Cost Capitalized Subsequent to Acquisition
Improvements	1,183,513
Gross Amount at Which Carried at Close of Period
Land	342,000
Building Improvements	2,551,182
Totals	2,893,182
Accumulated Depreciation	1,416,545
Commonwealth 1144 L.P. Residential Apartments Boston, Massachusetts
Deduct
Balance, Ending	9,149,680
Deduct:
Balance, Ending	4,851,194
Encumbrances (First Mortgages)	14,780,000
Initial Cost to Partnerships
Land	1,410,000
Building Improvements	5,664,816
Cost Capitalized Subsequent to Acquisition
Improvements	2,074,864
Gross Amount at Which Carried at Close of Period
Land	1,410,000
Building Improvements	7,739,680
Totals	9,149,680
Accumulated Depreciation	4,851,194
Executive Apartments L.P. Residential Apartments Framingham, Massachusetts
Deduct
Balance, Ending	1,504,045
Deduct:
Balance, Ending	1,056,717
Encumbrances (First Mortgages)	2,415,000
Initial Cost to Partnerships
Land	91,400
Building Improvements	740,360
Cost Capitalized Subsequent to Acquisition
Improvements	672,285
Gross Amount at Which Carried at Close of Period
Land	91,400
Building Improvements	1,412,645
Totals	1,504,045
Accumulated Depreciation	1,056,717
Hamilton Battle Green LLC Residential Apartments Lexington, Massachusetts
Deduct
Balance, Ending	9,928,822
Deduct:
Balance, Ending	1,409,607
Encumbrances (First Mortgages)	4,736,891
Initial Cost to Partnerships
Land	1,341,737
Building Improvements	8,457,497
Cost Capitalized Subsequent to Acquisition
Improvements	129,588
Gross Amount at Which Carried at Close of Period
Land	1,341,737
Building Improvements	8,587,085
Totals	9,928,822
Accumulated Depreciation	1,409,607
Hamilton Cypress LLC Commercial-1031Exchange Brookline, Massachusetts
Deduct
Balance, Ending	7,227,431
Deduct:
Balance, Ending	878,739
Initial Cost to Partnerships
Land	2,362,596
Building Improvements	4,613,985
Cost Capitalized Subsequent to Acquisition
Improvements	250,850
Gross Amount at Which Carried at Close of Period
Land	2,362,596
Building Improvements	4,864,835
Totals	7,227,431
Accumulated Depreciation	878,739
Hamilton Green Apartments Residential Apartments Andover, Massachusetts
Deduct
Balance, Ending	61,402,078
Deduct:
Balance, Ending	4,931,941
Encumbrances (First Mortgages)	38,500,000
Initial Cost to Partnerships
Land	16,054,336
Building Improvements	44,794,438
Cost Capitalized Subsequent to Acquisition
Improvements	553,304
Gross Amount at Which Carried at Close of Period
Land	16,054,336
Building Improvements	45,347,742
Totals	61,402,078
Accumulated Depreciation	4,931,941
Hamilton Linewt LLC Commercial-1031Exchange Newton, Massachusetts
Deduct
Balance, Ending	3,598,777
Deduct:
Balance, Ending	492,424
Initial Cost to Partnerships
Land	884,042
Building Improvements	2,652,127
Cost Capitalized Subsequent to Acquisition
Improvements	62,608
Gross Amount at Which Carried at Close of Period
Land	884,042
Building Improvements	2,714,735
Totals	3,598,777
Accumulated Depreciation	492,424
Hamilton Oaks Associates LLC Residential Apartments Brockton, Massachusetts
Deduct
Balance, Ending	16,638,080
Deduct:
Balance, Ending	8,036,862
Encumbrances (First Mortgages)	11,925,000
Initial Cost to Partnerships
Land	2,175,000
Building Improvements	12,325,000
Cost Capitalized Subsequent to Acquisition
Improvements	2,138,080
Gross Amount at Which Carried at Close of Period
Land	2,175,000
Building Improvements	14,463,080
Totals	16,638,080
Accumulated Depreciation	8,036,862
Highland Street Apartment, L.P. Residential Apartments Lowell, Massachusetts
Deduct
Balance, Ending	1,164,232
Deduct:
Balance, Ending	629,766
Encumbrances (First Mortgages)	1,050,000
Initial Cost to Partnerships
Land	156,000
Building Improvements	634,085
Cost Capitalized Subsequent to Acquisition
Improvements	374,147
Gross Amount at Which Carried at Close of Period
Land	156,000
Building Improvements	1,008,232
Totals	1,164,232
Accumulated Depreciation	629,766
Linhart L.P. Residential/Commercial Newton, Massachusetts
Deduct
Balance, Ending	3,203,713
Deduct:
Balance, Ending	1,945,771
Initial Cost to Partnerships
Land	385,000
Building Improvements	1,540,000
Cost Capitalized Subsequent to Acquisition
Improvements	1,278,713
Gross Amount at Which Carried at Close of Period
Land	385,000
Building Improvements	2,818,713
Totals	3,203,713
Accumulated Depreciation	1,945,771
NERA Dean St. Associates LLC Residential Apartments Norwood, Massachusetts
Deduct
Balance, Ending	8,004,571
Deduct:
Balance, Ending	2,893,369
Encumbrances (First Mortgages)	5,687,000
Initial Cost to Partnerships
Land	1,512,000
Building Improvements	5,701,480
Cost Capitalized Subsequent to Acquisition
Improvements	791,091
Gross Amount at Which Carried at Close of Period
Land	1,512,000
Building Improvements	6,492,571
Totals	8,004,571
Accumulated Depreciation	2,893,369
North Beacon 140 L.P. Residential Units Boston, Massachusetts
Deduct
Balance, Ending	6,516,240
Deduct:
Balance, Ending	3,476,883
Encumbrances (First Mortgages)	6,937,000
Initial Cost to Partnerships
Land	936,000
Building Improvements	3,762,013
Cost Capitalized Subsequent to Acquisition
Improvements	1,818,227
Gross Amount at Which Carried at Close of Period
Land	936,000
Building Improvements	5,580,240
Totals	6,516,240
Accumulated Depreciation	3,476,883
Olde English Apartments L.P. Residential Apartments Lowell, Massachusetts
Deduct
Balance, Ending	2,248,758
Deduct:
Balance, Ending	1,354,946
Encumbrances (First Mortgages)	3,080,000
Initial Cost to Partnerships
Land	46,181
Building Improvements	878,323
Cost Capitalized Subsequent to Acquisition
Improvements	1,324,254
Gross Amount at Which Carried at Close of Period
Land	46,181
Building Improvements	2,202,577
Totals	2,248,758
Accumulated Depreciation	1,354,946
Redwood Hills L.P. Residential Units Worcester, Massachusetts
Deduct
Balance, Ending	8,906,659
Deduct:
Balance, Ending	4,402,390
Encumbrances (First Mortgages)	6,743,000
Initial Cost to Partnerships
Land	1,200,000
Building Improvements	4,810,604
Cost Capitalized Subsequent to Acquisition
Improvements	2,896,055
Gross Amount at Which Carried at Close of Period
Land	1,200,000
Building Improvements	7,706,659
Totals	8,906,659
Accumulated Depreciation	4,402,390
River Drive L.P. Residential Apartments Danvers, Massachusetts
Deduct
Balance, Ending	1,339,247
Deduct:
Balance, Ending	919,183
Encumbrances (First Mortgages)	3,465,000
Initial Cost to Partnerships
Land	72,525
Building Improvements	587,777
Cost Capitalized Subsequent to Acquisition
Improvements	678,945
Gross Amount at Which Carried at Close of Period
Land	72,525
Building Improvements	1,266,722
Totals	1,339,247
Accumulated Depreciation	919,183
Riverside Apartments Condominium Units Massachusetts
Deduct
Balance, Ending	235,859
Deduct:
Balance, Ending	202,257
Initial Cost to Partnerships
Land	23,346
Building Improvements	190,807
Cost Capitalized Subsequent to Acquisition
Improvements	21,706
Gross Amount at Which Carried at Close of Period
Land	23,346
Building Improvements	212,513
Totals	235,859
Accumulated Depreciation	202,257
School St Assoc LLC Residential Apartments Framingham, Massachusetts
Deduct
Balance, Ending	21,851,711
Deduct:
Balance, Ending	7,285,429
Encumbrances (First Mortgages)	15,000,000
Initial Cost to Partnerships
Land	4,686,728
Building Improvements	18,746,911
Cost Capitalized Subsequent to Acquisition
Improvements	(1,581,928)
Gross Amount at Which Carried at Close of Period
Land	4,686,728
Building Improvements	17,164,983
Totals	21,851,711
Accumulated Depreciation	7,285,429
WRF Associates LLC Strip Mall Framingham, Massachusetts
Deduct
Balance, Ending	8,242,069
Deduct:
Balance, Ending	2,568,515
Encumbrances (First Mortgages)	6,000,000
Initial Cost to Partnerships
Land	3,280,000
Building Improvements	4,920,000
Cost Capitalized Subsequent to Acquisition
Improvements	42,069
Gross Amount at Which Carried at Close of Period
Land	3,280,000
Building Improvements	4,962,069
Totals	8,242,069
Accumulated Depreciation	2,568,515
WCB Associates LLC Residential Apartments Brockton, Massachusetts
Deduct
Balance, Ending	10,074,708
Deduct:
Balance, Ending	4,992,376
Encumbrances (First Mortgages)	7,000,000
Initial Cost to Partnerships
Land	1,335,000
Building Improvements	7,565,501
Cost Capitalized Subsequent to Acquisition
Improvements	1,174,207
Gross Amount at Which Carried at Close of Period
Land	1,335,000
Building Improvements	8,739,708
Totals	10,074,708
Accumulated Depreciation	4,992,376
Courtyard At Westgate Residential Units Burlington Massachusetts Member
Deduct
Balance, Ending	4,765,224
Deduct:
Balance, Ending	1,815,417
Encumbrances (First Mortgages)	2,500,000
Initial Cost to Partnerships
Land	44,965
Building Improvements	4,478,687
Cost Capitalized Subsequent to Acquisition
Improvements	241,572
Gross Amount at Which Carried at Close of Period
Land	44,965
Building Improvements	4,720,259
Totals	4,765,224
Accumulated Depreciation	1,815,417
Westgate Apartments LLC Residential Apartments Woburn, Massachusetts
Deduct
Balance, Ending	10,158,127
Deduct:
Balance, Ending	6,186,013
Encumbrances (First Mortgages)	15,700,000
Initial Cost to Partnerships
Land	461,300
Building Improvements	2,424,636
Cost Capitalized Subsequent to Acquisition
Improvements	7,316,384
Gross Amount at Which Carried at Close of Period
Land	417,107
Building Improvements	9,741,020
Totals	10,158,127
Accumulated Depreciation	$ 6,186,013