Name:	nen_DistributionAndLossInExcessOfInvestmentInUnconsolidatedJointVenture
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Sum of the carrying values as of the balance sheet date of obligations incurred through that date, including liabilities incurred and payable to vendors for goods and services received, taxes, interest, rent and utilities, compensation costs, payroll taxes and fringe benefits (other than pension and postretirement obligations), contractual rights and obligations, and statutory obligations.

No definition available.

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For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

No definition available.

Name:	nen_EquityMethodInvestmentSummarizedFinancialInformationAccountsReceivableNet
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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

No definition available.

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Refundable consideration, usually cash, held by the entity pending satisfactory completion of the entity's obligations or pending the closing of a contract.

No definition available.

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This element represents the deferred financing and leasing cost incurred by the entity during the reporting period.

No definition available.

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The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy.

No definition available.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets.

No definition available.

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Carrying amount of income producing properties held for rental.

No definition available.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

No definition available.

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Represents the number of units retained for long-term investment.

No definition available.

Name:	nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment
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Data Type:	xbrli:integerItemType
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Represents the number of units sold.

No definition available.

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Represents the number of units to be sold.

No definition available.

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Represents the number of units unsold by the entity.

No definition available.

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Represents the net share of partners capital in unconsolidated joint venture investments.

No definition available.

Name:	nen_PartnersCapitalAccountShareInInvestmentsNet
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Balance Type:	debit
Period Type:	instant

Name:	nen_UnitsInRealEstatePropertyAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The amount of assets reported by an equity method investment of the entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Topic 235

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Amount of equity, excluding noncontrolling interest, attributable to the equity method investment of the entity.

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The amount of liabilities reported by an equity method investment of the entity.

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Data Type:	xbrli:monetaryItemType
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The amount of liabilities and equity reported by an equity method investment of the entity.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Data Type:	xbrli:stringItemType
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The number of units in a real estate property owned as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfUnitsInRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
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Period Type:	instant

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