Represents the amount of allowance for doubtful accounts related to rents receivable.

No definition available.

Name:	nen_OperatingLeasesAllowanceForDoubtfulRentReceivable
Namespace Prefix:	nen_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of amortization of deferred rents.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesAmortizationOfDeferredRents
Namespace Prefix:	nen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the amount of annual rent to be receivable for leases to be expired.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesAnnualBaseRentForExpiringLeases
Namespace Prefix:	nen_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the deferred rental concessions on real estate properties.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesDeferralOfRentalConcession
Namespace Prefix:	nen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the maximum period of non-cancellable operating leases.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesNoncancelableMaximumLeaseTerm
Namespace Prefix:	nen_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of leases to be expired.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesNumberOfLeasesExpiring
Namespace Prefix:	nen_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of annual base rent for leases to be expired.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesPercentageOfAnnualBaseRentForExpiringLeases
Namespace Prefix:	nen_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of rental income related to commercial real estate property.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesPercentageOfRentalIncomeRelatedToCommercialProperty
Namespace Prefix:	nen_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of rental income related to residential real estate property.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesPercentageOfRentalIncomeRelatedToResidentialPropertyAndCondominiumUnits
Namespace Prefix:	nen_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount resulting from recognizing rental income from non-cancelable commercial leases with future rental increases on a straight-line basis, which is included in rents receivable.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesRentalIncomeWithFutureRentalIncreases
Namespace Prefix:	nen_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the square feet area of rental properties for which leases are to be expired.

+ References

No definition available.

+ Details

Name:	nen_OperatingLeasesSquareFeetForExpiringLeases
Namespace Prefix:	nen_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_OperatingLeasedAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Future minimum rental payments in aggregate as of the balance sheet date under operating leases.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Future rental payments receivable within one year of the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within the fifth year from the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within the fourth year from the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within the third year from the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within the second year from the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future minimum lease payments receivable under operating leases for periods greater than five years following the balance sheet date.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of contingent rental revenue recognized for the period under lease, based on the occurrences of an event or condition.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718

+ Details

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

- Details

Name:	nen_OperatingLeasesExpirationPeriodAxis=nen_OperatingLeasesExpirationPeriodYearFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	nen_OperatingLeasesExpirationPeriodAxis=nen_OperatingLeasesExpirationPeriodYearFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	nen_OperatingLeasesExpirationPeriodAxis=nen_OperatingLeasesExpirationPeriodYearNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	nen_OperatingLeasesExpirationPeriodAxis=nen_OperatingLeasesExpirationPeriodYearOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	nen_OperatingLeasesExpirationPeriodAxis=nen_OperatingLeasesExpirationPeriodYearSevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	nen_OperatingLeasesExpirationPeriodAxis=nen_OperatingLeasesExpirationPeriodYearSixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	nen_OperatingLeasesExpirationPeriodAxis=nen_OperatingLeasesExpirationPeriodYearThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	nen_OperatingLeasesExpirationPeriodAxis=nen_OperatingLeasesExpirationPeriodYearTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
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RENTAL INCOME (Details) (USD $)	12 Months Ended
RENTAL INCOME (Details) (USD $)	Dec. 31, 2014 sqft item	Dec. 31, 2013	Dec. 31, 2012
RENTAL INCOME
Allowance for doubtful rent receivable	$ 366,000	$ 344,000
Annual base rent for expiring leases	2,978,995
Total square feet for expiring leases	108,043
Total number of leases expiring	44
Percentage of annual base rent for expiring leases	100.00%
Recognizing rental income from non-cancelable commercial leases with future rental increases on a straight-line basis	163,000
Deferred rental concession	109,000
Amortization of deferred rents	2,000
Minimum future rental income
2015	2,699,000
2016	2,218,000
2017	1,510,000
2018	1,181,000
2019	724,000
Thereafter	746,000
Commercial Property Leases	9,078,000
Percentage of rental income related to residential apartments and condominium units with leases of one year or less	92.00%
Maximum period of non-cancelable operating lease	1 year
Percentage of rental income related to commercial properties	8.00%
Aggregate contingent rentals from continuing operations	638,000	670,000	661,000
Through December 31, 2015
RENTAL INCOME
Annual base rent for expiring leases	452,620
Total square feet for expiring leases	21,266
Total number of leases expiring	11
Percentage of annual base rent for expiring leases	16.00%
Through December 31, 2016
RENTAL INCOME
Annual base rent for expiring leases	628,628
Total square feet for expiring leases	28,600
Total number of leases expiring	7
Percentage of annual base rent for expiring leases	21.00%
Through December 31, 2017
RENTAL INCOME
Annual base rent for expiring leases	569,511
Total square feet for expiring leases	16,516
Total number of leases expiring	8
Percentage of annual base rent for expiring leases	19.00%
Through December 31, 2018
RENTAL INCOME
Annual base rent for expiring leases	298,551
Total square feet for expiring leases	8,707
Total number of leases expiring	6
Percentage of annual base rent for expiring leases	10.00%
Through December 31, 2019
RENTAL INCOME
Annual base rent for expiring leases	742,785
Total square feet for expiring leases	25,277
Total number of leases expiring	9
Percentage of annual base rent for expiring leases	25.00%
Through December 31, 2020
RENTAL INCOME
Annual base rent for expiring leases	64,657
Total square feet for expiring leases	1,106
Total number of leases expiring	1
Percentage of annual base rent for expiring leases	2.00%
Through December 31, 2021
RENTAL INCOME
Annual base rent for expiring leases	64,800
Total square feet for expiring leases	1,800
Total number of leases expiring	1
Percentage of annual base rent for expiring leases	2.00%
Through December 31, 2023
RENTAL INCOME
Annual base rent for expiring leases	$ 157,443
Total square feet for expiring leases	4,771
Total number of leases expiring	1
Percentage of annual base rent for expiring leases	5.00%