Represents the increase in aggregate indebtedness of the subsidiaries and joint ventures.

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Represents the ratio of consolidated adjusted earnings before interest, taxes, depreciation and amortization to interest expense, which is necessary to be maintained under the terms of the senior credit facilities' covenants.

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Represents the ratio of consolidated total debt to consolidated adjusted earnings before, interest, taxes, depreciation and amortization allowed under the terms of the senior credit facilities' covenants.

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Represents the amount of loan proceeds and cash reserves of the Partnership utilized to pay down the existing Line of Credit.

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No definition available.

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Represents the percentage points added to the reference rate to compute the variable rate which is used in calculation of base rate on the debt instrument.

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No definition available.

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Represents amount withdrawn by the entity from the line of credit.

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Represents the percentage of pledged interests of the Partnership's ownership interest.

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Represents the ratio of net operating income to total indebtedness.

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Represents the level of tangible net worth required to maintain.

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No definition available.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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Amount of the fee that accompanies borrowing money under the debt instrument.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of the cost of borrowed funds accounted for as interest expense.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Amount of the fee for available but unused credit capacity under the credit facility.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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The number of real estate properties owned as of the balance sheet date.

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The cash outflow for the settlement of obligation drawn from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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MORTGAGE NOTES PAYABLE (Line of Credit) (Details)						1 Months Ended			12 Months Ended
MORTGAGE NOTES PAYABLE (Line of Credit) (Details)	Jun. 04, 2018 USD ($)	Sep. 29, 2017 USD ($)	Jan. 15, 2016 USD ($)	Jan. 07, 2016 USD ($)	Jul. 31, 2014 USD ($)	Jan. 31, 2019 USD ($)	Oct. 31, 2018 USD ($)	Jul. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 29, 2018 USD ($)	Jul. 16, 2017 USD ($)	Jul. 06, 2017 USD ($)
Line of Credit
Interest expense									$ 12,389,680	$ 11,114,146	$ 10,200,393
Payment on line of credit									15,000,000	24,000,000	$ 25,000,000
Credit line balance										$ 2,000,000
Subsequent event
Line of Credit
Payment on line of credit						$ 2,000,000
Woodland Park Apartments LLC Newton Massachusetts
Line of Credit
Term of debt		30 years
Loan amount		$ 22,250,000											$ 16,000,000	$ 16,000,000
Interest expense									182,000
Credit line balance														$ 25,000,000
Hamilton Highlands LLC Residential Needham Massachusetts [Member]
Line of Credit
Loan amount												$ 21,500,000
Credit line balance												8,000,000
Residences at Captain Parkers LLC Residential Apartments Lexington, Massachusetts
Line of Credit
Credit line balance				$ 0
Amount of loan proceeds and cash reserves utilized to pay off the existing line of credit			$ 2,000,000	23,000,000
LIBOR \| Residences at Captain Parkers LLC Residential Apartments Lexington, Massachusetts
Line of Credit
Loan amount				$ 20,071,000
LIBOR \| Residences at Captain Parkers LLC Residential Apartments Lexington, Massachusetts
Line of Credit
Margin over basis of interest rate (as a percent)				2.01%
Line of Credit
Line of Credit
Maximum borrowings					$ 25,000,000
Term of debt					3 years
Payment on line of credit		8,000,000					$ 3,000,000	$ 4,000,000
Amount of refinancing costs									128,000
Credit line balance									$ 2,000,000				25,000,000
Number of properties in which borrowing amount collateralized \| item									23
Commitment fee									$ 27,000
Line of Credit \| Dexter Park
Line of Credit
Payment on line of credit	$ 16,000,000
Line of Credit \| Woodland Park Apartments LLC Newton Massachusetts
Line of Credit
Payment on line of credit		8,000,000
Funds drawn by the company		$ 25,000,000											$ 16,000,000
Line of Credit \| Hamilton Highlands LLC Residential Needham Massachusetts [Member]
Line of Credit
Funds drawn by the company												$ 8,000,000
Line of Credit \| Federal Funds Rate
Line of Credit
Basis of effective interest rate used in calculation of Base Rate (as a percent)					0.50%
Line of Credit \| LIBOR
Line of Credit
Basis of effective interest rate used in calculation of Base Rate (as a percent)					1.00%
Margin over basis of interest rate (as a percent)					2.50%
Line of Credit \| Minimum
Line of Credit
Pledged interests of the Partnership's ownership interest (as a percent)									49.00%
Commitment fee for unused amount (as a percent)									0.15%
Tangible net worth									$ 150,000,000
Ratio of net operating income to total indebtedness									9.50%
Debt service coverage ratio									1.6
Line of Credit \| Maximum
Line of Credit
Pledged interests of the Partnership's ownership interest (as a percent)									100.00%
Commitment fee for unused amount (as a percent)									0.20%
Leverage ratio									65.00%
Aggregate increase in indebtedness									$ 15,000,000