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Represents the contribution required to pay off the remaining balance of debt.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Represents the amount of loan proceeds utilized for paying off the existing mortgage.

No definition available.

Name:	nen_DebtInstrumentLoanProceedsUtilizedToPayOffExistingMortgage
Namespace Prefix:	nen_
Data Type:	xbrli:monetaryItemType
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Represents the period for which the entity is required to make interest only payments on the debt instrument.

No definition available.

Name:	nen_DebtInstrumentTermForWhichInterestOnlyPaymentsRequired
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Data Type:	xbrli:durationItemType
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Represents the cash back portion of the mortgage loan.

No definition available.

Name:	nen_ProceedsFromLoan
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Data Type:	xbrli:monetaryItemType
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Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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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.

No definition available.

Name:	us-gaap_DebtInstrumentTerm
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Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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The cash outflow for incremental, external costs directly pertaining to an early extinguishment of debt, including legal costs and prepayment penalties, and excluding interest and repayment of debt principal.

No definition available.

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Data Type:	xbrli:monetaryItemType
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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

No definition available.

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_LinhartLPResidentialCommercialNewtonMassachusettsMember
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Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
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