INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Balance Sheet) (Details)	Sep. 30, 2021 USD ($) property	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($) property	Dec. 31, 2019 USD ($)	May 31, 2018 USD ($)	Oct. 28, 2009 USD ($) item	Mar. 07, 2005 item	Mar. 02, 2005 USD ($) item	Sep. 30, 2004 USD ($) item	Aug. 31, 2004 USD ($) item	Nov. 30, 2001 USD ($) item
ASSETS
Rental Properties	$ 255,114,078	$ 264,609,887
Cash and Cash Equivalents	24,616,257	18,646,972
Rents Receivable	1,003,672	1,412,074
Real Estate Tax Escrows	567,911	534,941
Prepaid Expenses and Other Assets	6,170,342	5,054,959
Total Assets	288,891,234	291,669,602
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Notes Payable	281,919,669	283,444,533
Accounts Payable and Accrued Expenses	4,301,420	3,888,237
Advance Rental Payments and Security Deposits	7,711,022	7,466,134
Total Liabilities	333,666,534	333,138,647
Partners' Capital	(44,775,300)	(41,469,045)	$ (39,330,161)	$ (37,823,787)
Total Liabilities and Partners' Capital	288,891,234	291,669,602
Investment in Unconsolidated Joint Ventures	1,418,974	1,410,769
Distribution and Loss in Excess of investments in Unconsolidated Joint Venture	$ (22,734,423)	$ (21,339,743)
NERA 50%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	50.00%		50.00%
NERA 40%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	40.00%		40.00%
Investment Properties
ASSETS
Rental Properties	$ 112,651,474		$ 116,833,825
Cash and Cash Equivalents	3,436,649		4,240,170
Rents Receivable	392,089		830,257
Real Estate Tax Escrows	297,534		246,827
Prepaid Expenses and Other Assets	2,684,999		2,085,019
Total Assets	119,462,745		124,236,098
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Notes Payable	166,230,563		166,332,832
Accounts Payable and Accrued Expenses	1,228,687		1,167,605
Advance Rental Payments and Security Deposits	3,493,954		3,067,704
Total Liabilities	170,953,204		170,568,141
Partners' Capital	(51,490,459)		(46,332,043)
Total Liabilities and Partners' Capital	119,462,745		124,236,098
Investment in Unconsolidated Joint Ventures	1,418,974		1,439,697
Distribution and Loss in Excess of investments in Unconsolidated Joint Venture	(22,734,423)		(20,505,288)
Total Investment in Unconsolidated Joint Ventures (Net)	$ (21,315,449)		$ (19,065,591)
Total units/ condominiums
Total | property	865		865
Units to be retained | property	690		690
Units to be sold | property	175		175
Total number of units sold | property	175		175
Investment Properties | Residential buildings
Total units/ condominiums
Total | property	862		862
Investment Properties | Commercial
Total units/ condominiums
Total | property	3		3
Hamilton Essex 81
ASSETS
Rental Properties	$ 6,376,891		$ 6,758,283
Cash and Cash Equivalents	230,394		281,585
Rents Receivable	65,313		220,578
Real Estate Tax Escrows	77,685		66,248
Prepaid Expenses and Other Assets	311,513		319,434
Total Assets	7,061,796		7,646,128
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Notes Payable	9,944,844		9,931,055
Accounts Payable and Accrued Expenses	82,137		53,569
Advance Rental Payments and Security Deposits	189,746		202,659
Total Liabilities	10,216,727		10,187,283
Partners' Capital	(3,154,931)		(2,541,155)
Total Liabilities and Partners' Capital	7,061,796		$ 7,646,128
Partners' Capital % - NERA			50.00%
Distribution and Loss in Excess of investments in Unconsolidated Joint Venture	$ (1,577,467)		$ (1,270,579)
Total units/ condominiums
Total	49		49				48
Units to be retained | property	49		49
Hamilton Essex 81 | NERA 50%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	50.00%
Hamilton Essex 81 | Residential buildings
Total units/ condominiums
Total | property	48		48
Hamilton Essex 81 | Commercial
Total units/ condominiums
Total | property	1		1
Hamilton Essex Development
ASSETS
Rental Properties	$ 2,588,792		$ 2,591,281
Cash and Cash Equivalents	73,049		70,894
Rents Receivable	13,744		48,878
Prepaid Expenses and Other Assets	67,410		84,898
Total Assets	2,742,995		2,795,951
LIABILITIES AND PARTNERS' CAPITAL
Accounts Payable and Accrued Expenses	2,250		2,400
Total Liabilities	2,250		2,400
Partners' Capital	2,740,745		2,793,551
Total Liabilities and Partners' Capital	2,742,995		$ 2,795,951
Partners' Capital % - NERA			50.00%
Investment in Unconsolidated Joint Ventures	$ 1,370,373		$ 1,396,776
Total units/ condominiums
Total | property	1		1
Units to be retained | property	1		1
Hamilton Essex Development | NERA 50%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	50.00%
Hamilton Essex Development | Commercial
Total units/ condominiums
Total | property	1		1
345 Franklin
ASSETS
Rental Properties	$ 5,139,866		$ 5,439,844
Cash and Cash Equivalents	154,633		183,638
Rents Receivable	23,113		11,367
Real Estate Tax Escrows	62,506		57,079
Prepaid Expenses and Other Assets	123,115		82,969
Total Assets	5,503,233		5,774,897
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Notes Payable	8,944,849		9,149,766
Accounts Payable and Accrued Expenses	99,583		101,651
Advance Rental Payments and Security Deposits	247,951		217,832
Total Liabilities	9,292,383		9,469,249
Partners' Capital	(3,789,150)		(3,694,352)
Total Liabilities and Partners' Capital	5,503,233		$ 5,774,897
Partners' Capital % - NERA			50.00%								50.00%
Investment in Unconsolidated Joint Ventures											$ 1,533,000
Distribution and Loss in Excess of investments in Unconsolidated Joint Venture	$ (1,894,576)		$ (1,847,175)
Total units/ condominiums
Total	40		40								40
Units to be retained | property	40		40
345 Franklin | NERA 50%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	50.00%
345 Franklin | Residential buildings
Total units/ condominiums
Total | property	40		40
Hamilton 1025
ASSETS
Rental Properties	$ 82,371		$ 85,635
Cash and Cash Equivalents	9,776		12,305
Rents Receivable	7,081		811
Prepaid Expenses and Other Assets	685		2,129
Total Assets	99,913		100,880
LIABILITIES AND PARTNERS' CAPITAL
Accounts Payable and Accrued Expenses	2,711		15,038
Total Liabilities	2,711		15,038
Partners' Capital	97,202		85,842
Total Liabilities and Partners' Capital	99,913		$ 100,880
Partners' Capital % - NERA			50.00%					50.00%
Investment in Unconsolidated Joint Ventures	$ 48,601		$ 42,921					$ 2,352,000
Total units/ condominiums
Total	176		176					176
Units to be retained	1		1					(49)
Units to be sold | property	175		175
Total number of units sold | property	175		175
Hamilton 1025 | NERA 50%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	50.00%
Hamilton 1025 | Residential buildings
Total units/ condominiums
Total | property	175		175
Hamilton 1025 | Commercial
Total units/ condominiums
Total | property	1		1
Hamilton Minuteman
ASSETS
Rental Properties	$ 4,766,334		$ 5,077,525
Cash and Cash Equivalents	231,357		210,705
Rents Receivable	7,285
Real Estate Tax Escrows	40,025		31,378
Prepaid Expenses and Other Assets	30,592		26,428
Total Assets	5,075,593		5,346,036
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Notes Payable	5,918,506		5,910,322
Accounts Payable and Accrued Expenses	67,629		64,341
Advance Rental Payments and Security Deposits	154,400		157,932
Total Liabilities	6,140,535		6,132,595
Partners' Capital	(1,064,942)		(786,559)
Total Liabilities and Partners' Capital	5,075,593		$ 5,346,036
Partners' Capital % - NERA			50.00%						50.00%
Investment in Unconsolidated Joint Ventures									$ 5,075,000
Distribution and Loss in Excess of investments in Unconsolidated Joint Venture	$ (532,471)		$ (393,280)
Total units/ condominiums
Total	42		42						42
Units to be retained | property	42		42
Hamilton Minuteman | NERA 50%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	50.00%
Hamilton Minuteman | Residential buildings
Total units/ condominiums
Total | property	42		42
Hamilton on Main Apts
ASSETS
Rental Properties	$ 14,522,033		$ 15,343,928
Cash and Cash Equivalents	602,344		610,816
Rents Receivable	38,832		46,780
Real Estate Tax Escrows	117,318		92,122
Prepaid Expenses and Other Assets	195,099		162,421
Total Assets	15,475,626		16,256,067
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Notes Payable	16,853,184		16,837,132
Accounts Payable and Accrued Expenses	169,515		168,318
Advance Rental Payments and Security Deposits	474,463		435,679
Total Liabilities	17,497,162		17,441,129
Partners' Capital	(2,021,536)		(1,185,062)
Total Liabilities and Partners' Capital	15,475,626		$ 16,256,067
Partners' Capital % - NERA			50.00%							50.00%
Investment in Unconsolidated Joint Ventures										$ 8,000,000
Distribution and Loss in Excess of investments in Unconsolidated Joint Venture	$ (1,010,769)		$ (592,531)
Total units/ condominiums
Total	148		148							280
Units to be retained | property	148		148
Hamilton on Main Apts | NERA 50%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	50.00%
Hamilton on Main Apts | Residential buildings
Total units/ condominiums
Total | property	148		148
Dexter Park
ASSETS
Rental Properties	$ 79,175,187		$ 81,537,329
Cash and Cash Equivalents	2,135,096		2,870,227
Rents Receivable	236,721		501,843
Prepaid Expenses and Other Assets	1,956,585		1,406,740
Total Assets	83,503,589		86,316,139
LIABILITIES AND PARTNERS' CAPITAL
Mortgage Notes Payable	124,569,180		124,504,557		$ 82,000,000
Accounts Payable and Accrued Expenses	804,862		762,288
Advance Rental Payments and Security Deposits	2,427,394		2,053,602
Total Liabilities	127,801,436		127,320,447
Partners' Capital	(44,297,847)		(41,004,308)
Total Liabilities and Partners' Capital	83,503,589		$ 86,316,139
Partners' Capital % - NERA			40.00%			40.00%
Investment in Unconsolidated Joint Ventures						$ 15,925,000
Distribution and Loss in Excess of investments in Unconsolidated Joint Venture	$ (17,719,140)		$ (16,401,724)
Total units/ condominiums
Total	409		409			409
Units to be retained | property	409		409
Dexter Park | NERA 40%
LIABILITIES AND PARTNERS' CAPITAL
Partners' Capital % - NERA	40.00%
Dexter Park | Residential buildings
Total units/ condominiums
Total | property	409		409