SIGNIFICANT ACCOUNTING POLICIES (Details) - Jun. 30, 2015	ft² item
Residential and mixed-use properties
Line of Business
Number of properties	20
Total	2,412
Condominium
Line of Business
Total	19
Wholly owned properties
Line of Business
Number of properties	24
Wholly owned properties \| Residential buildings
Line of Business
Number of properties	16
Total	2,412
Wholly owned properties \| Mixed use residential, retail and office buildings
Line of Business
Number of properties	4
Wholly owned properties \| Commercial
Line of Business
Number of properties	3
Area of property (in square feet) \| ft²	108,043
Wholly owned properties \| Condominium
Line of Business
Number of properties	1
Total	19
Partially owned properties \| Residential and mixed-use properties
Line of Business
Number of properties	9
Total	790
Area of property (in square feet) \| ft²	12,500
Partially owned properties \| Residential and mixed-use properties \| Minimum
Line of Business
Percentage of ownership interest	40.00%
Partially owned properties \| Residential and mixed-use properties \| Maximum
Line of Business
Percentage of ownership interest	50.00%
Partially owned properties \| Car parking lot
Line of Business
Capacity of real estate property (in cars per lot)	50

Represents the capacity of real estate property.

No definition available.

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- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of units in a real estate property owned as of the balance sheet date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Details

Name:	us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=nen_ResidentialAndMixedUseRealEstateMember
Namespace Prefix:
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- Details

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- Details

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- Details

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- Details

Name:	us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=nen_ResidentialRetailAndOfficeBuildingMixedUseMember
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- Details

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- Details

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- Details

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- Details

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- Details

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