RENTAL PROPERTIES (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	$ 138,055,522
Initial Cost to Partnerships
Land	25,799,080
Building Improvements	105,534,296
Cost Capitalized Subsequent to Acquisition
Improvements	28,587,184
Gross Amount at Which Carried at Close of Period
Land	25,754,887
Building Improvements	134,121,480
Totals	159,876,367
Accumulated Depreciation	64,440,518
Rental Properties
Balance, Beginning	159,123,799	150,818,648	150,411,555
Additions:
Buildings, improvements and other assets	2,360,399	12,444,604	2,268,039
Balance before deductions	161,484,198	163,263,252	152,679,594
Deduct:
Write-off of retired or disposed assets	1,607,830	2,437,555	1,860,946
Rental properties held for sale and/or sold		1,701,898
Balance, Ending	159,876,368	159,123,799	150,818,648
Accumulated Depreciation
Balance, Beginning	60,199,265	58,074,391	54,439,618
Add:
Depreciation for the year	5,849,083	5,750,989	5,495,719
Total additions	66,048,348	63,825,380	59,935,337
Deduct:
Accumulated depreciation of retired or disposed assets	1,607,830	2,437,555	1,860,946
Accumulated depreciation of rental properties held for sale and/or sold		1,188,560
Balance, Ending	64,440,518	60,199,265	58,074,391
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	20 years
Boylston Downtown L.P. Residential Apartments Boston, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	19,500,000
Initial Cost to Partnerships
Land	2,112,000
Building Improvements	8,593,111
Cost Capitalized Subsequent to Acquisition
Improvements	7,116,107
Gross Amount at Which Carried at Close of Period
Land	2,112,000
Building Improvements	15,709,218
Totals	17,821,218
Accumulated Depreciation	9,086,787
Brookside Associates LLC Residential Apartments Woburn, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	2,723,830
Initial Cost to Partnerships
Land	684,000
Building Improvements	3,116,000
Cost Capitalized Subsequent to Acquisition
Improvements	492,070
Gross Amount at Which Carried at Close of Period
Land	684,000
Building Improvements	3,608,070
Totals	4,292,070
Accumulated Depreciation	1,621,108
Courtyard @ Westgate Residential Units Burlington, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	2,000,000
Initial Cost to Partnerships
Land	44,965
Building Improvements	4,478,687
Cost Capitalized Subsequent to Acquisition
Improvements	253,696
Gross Amount at Which Carried at Close of Period
Land	44,965
Building Improvements	4,732,383
Totals	4,777,348
Accumulated Depreciation	1,465,723
Clovelly Apartments L.P. Residential Apartments Nashua, New Hampshire
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	4,160,000
Initial Cost to Partnerships
Land	177,610
Building Improvements	1,478,359
Cost Capitalized Subsequent to Acquisition
Improvements	1,268,279
Gross Amount at Which Carried at Close of Period
Land	177,610
Building Improvements	2,746,638
Totals	2,924,248
Accumulated Depreciation	1,981,658
Commonwealth 1137 L.P. Residential Apartments Boston, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	3,750,000
Initial Cost to Partnerships
Land	342,000
Building Improvements	1,367,669
Cost Capitalized Subsequent to Acquisition
Improvements	933,759
Gross Amount at Which Carried at Close of Period
Land	342,000
Building Improvements	2,301,428
Totals	2,643,428
Accumulated Depreciation	1,251,632
Commonwealth 1144 L.P. Residential Apartments Boston, Massachusetts
Real estate and accumulated depreciation
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	1,616,613
Gross Amount at Which Carried at Close of Period
Land	1,410,000
Building Improvements	7,281,429
Totals	8,691,429
Accumulated Depreciation	4,373,285
Condominium Units-Riverside Residential Units Massachusetts
Initial Cost to Partnerships
Land	23,346
Building Improvements	190,807
Cost Capitalized Subsequent to Acquisition
Improvements	22,428
Gross Amount at Which Carried at Close of Period
Land	23,346
Building Improvements	213,235
Totals	236,581
Accumulated Depreciation	205,326
Executive Apartments L.P. Residential Apartments Framingham, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	2,415,000
Initial Cost to Partnerships
Land	91,400
Building Improvements	740,360
Cost Capitalized Subsequent to Acquisition
Improvements	758,449
Gross Amount at Which Carried at Close of Period
Land	91,400
Building Improvements	1,498,809
Totals	1,590,209
Accumulated Depreciation	1,128,556
Hamilton Battle Green LLC Residential Apartments Lexington, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	4,893,448
Initial Cost to Partnerships
Land	1,341,737
Building Improvements	8,457,497
Cost Capitalized Subsequent to Acquisition
Improvements	31,849
Gross Amount at Which Carried at Close of Period
Land	1,341,737
Building Improvements	8,489,346
Totals	9,831,083
Accumulated Depreciation	612,568
Hamilton Cypress LLC Commercial-1031Exchange Brookline, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	3,686,380
Initial Cost to Partnerships
Land	2,362,596
Building Improvements	4,613,985
Cost Capitalized Subsequent to Acquisition
Improvements	51,823
Gross Amount at Which Carried at Close of Period
Land	2,362,596
Building Improvements	4,665,808
Totals	7,028,404
Accumulated Depreciation	696,283
Hamilton Linewt LLC Commercial-1031Exchange Newton, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	1,528,429
Initial Cost to Partnerships
Land	884,042
Building Improvements	2,652,127
Cost Capitalized Subsequent to Acquisition
Improvements	50,608
Gross Amount at Which Carried at Close of Period
Land	884,042
Building Improvements	2,702,735
Totals	3,586,777
Accumulated Depreciation	353,574
Hamilton Oaks Associates LLC Residential Apartments Brockton, Massachusetts
Real estate and accumulated depreciation
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	1,726,607
Gross Amount at Which Carried at Close of Period
Land	2,175,000
Building Improvements	14,051,607
Totals	16,226,607
Accumulated Depreciation	7,256,645
Highland Street Apartment, L.P. Residential Apartments Lowell, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	1,050,000
Initial Cost to Partnerships
Land	156,000
Building Improvements	634,085
Cost Capitalized Subsequent to Acquisition
Improvements	400,178
Gross Amount at Which Carried at Close of Period
Land	156,000
Building Improvements	1,034,263
Totals	1,190,263
Accumulated Depreciation	569,822
Linhart L.P. Residential/Commercial Newton, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	1,964,119
Initial Cost to Partnerships
Land	385,000
Building Improvements	1,540,000
Cost Capitalized Subsequent to Acquisition
Improvements	1,157,151
Gross Amount at Which Carried at Close of Period
Land	385,000
Building Improvements	2,697,151
Totals	3,082,151
Accumulated Depreciation	1,769,651
Nashoba Apartments L.P. Residential Apartments Acton, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	2,000,000
Initial Cost to Partnerships
Land	79,650
Building Improvements	284,548
Cost Capitalized Subsequent to Acquisition
Improvements	887,277
Gross Amount at Which Carried at Close of Period
Land	79,650
Building Improvements	1,171,825
Totals	1,251,475
Accumulated Depreciation	789,226
NERA Dean St. Associates LLC Residential Apartments Norwood, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	5,213,958
Initial Cost to Partnerships
Land	1,512,000
Building Improvements	5,701,480
Cost Capitalized Subsequent to Acquisition
Improvements	426,220
Gross Amount at Which Carried at Close of Period
Land	1,512,000
Building Improvements	6,127,700
Totals	7,639,700
Accumulated Depreciation	2,477,008
North Beacon 140 L.P. Residential Units Boston, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	6,937,000
Initial Cost to Partnerships
Land	936,000
Building Improvements	3,762,013
Cost Capitalized Subsequent to Acquisition
Improvements	1,490,223
Gross Amount at Which Carried at Close of Period
Land	936,000
Building Improvements	5,252,236
Totals	6,188,236
Accumulated Depreciation	3,120,665
Olde English Apartments L.P. Residential Apartments Lowell, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	3,080,000
Initial Cost to Partnerships
Land	46,181
Building Improvements	878,323
Cost Capitalized Subsequent to Acquisition
Improvements	1,161,011
Gross Amount at Which Carried at Close of Period
Land	46,181
Building Improvements	2,039,334
Totals	2,085,515
Accumulated Depreciation	1,345,108
River Drive L.P. Residential Apartments Danvers, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	3,465,000
Initial Cost to Partnerships
Land	72,525
Building Improvements	587,777
Cost Capitalized Subsequent to Acquisition
Improvements	1,426,304
Gross Amount at Which Carried at Close of Period
Land	72,525
Building Improvements	2,014,081
Totals	2,086,606
Accumulated Depreciation	1,601,231
Redwood Hills L.P. Residential Units Worcester, Massachusetts
Real estate and accumulated depreciation
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	2,117,589
Gross Amount at Which Carried at Close of Period
Land	1,200,000
Building Improvements	6,928,193
Totals	8,128,193
Accumulated Depreciation	4,055,659
School St Assoc LLC Residential Apartments Framingham, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	15,308,474
Initial Cost to Partnerships
Land	4,686,728
Building Improvements	18,746,911
Cost Capitalized Subsequent to Acquisition
Improvements	(1,928,307)
Gross Amount at Which Carried at Close of Period
Land	4,686,728
Building Improvements	16,818,604
Totals	21,505,332
Accumulated Depreciation	6,112,019
Staples Plaza Strip Mall Framingham, Massachusetts
Real estate and accumulated depreciation
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	36,724
Gross Amount at Which Carried at Close of Period
Land	3,280,000
Building Improvements	4,956,724
Totals	8,236,724
Accumulated Depreciation	2,235,613
WCB Associates LLC Residential Apartments Brockton, Massachusetts
Real estate and accumulated depreciation
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	1,083,048
Gross Amount at Which Carried at Close of Period
Land	1,335,000
Building Improvements	8,648,549
Totals	9,983,549
Accumulated Depreciation	4,552,121
Westgate Apartments LLC Residential Apartments Woburn, Massachusetts
Real estate and accumulated depreciation
Encumbrances (First Mortgages)	7,931,885
Initial Cost to Partnerships
Land	461,300
Building Improvements	2,424,636
Cost Capitalized Subsequent to Acquisition
Improvements	6,007,478
Gross Amount at Which Carried at Close of Period
Land	417,107
Building Improvements	8,432,114
Totals	8,849,221
Accumulated Depreciation	$ 5,779,250