Represents the amount of quarterly fee for asset management consulting services.

No definition available.

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

- Definition

Represents the amount aggregate cost of construction, architectural services and supervision of capital projects during the reporting period.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of limited partnerships and limited liability companies in which the entity has made investments which are accounted for using the equity method of consolidation.

+ References

No definition available.

+ Details

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

- Definition

This element represents the amount of management fee incurred for payment to a management company during the reporting period.

+ References

No definition available.

+ Details

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

- Definition

Number of employees, excluding President, having ownership interest in the investment properties.

+ References

No definition available.

+ Details

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

- Definition

Represents the amount of expense charged to entity for bookkeeping and accounting services under terms of agreement with related parties, included within administrative costs.

+ References

No definition available.

+ Details

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

- Definition

Represents the amount charged for bookkeeping and accounting services per year as included in administrative expenses.

+ References

No definition available.

+ Details

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

- Definition

Represents the charge against earnings towards management fees associated with the services provided by related party.

+ References

No definition available.

+ Details

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

- Definition

Represents the management fees expressed as a percentage of Linewt.

+ References

No definition available.

+ Details

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

- Definition

Represents the management fee expressed as a percentage of rental revenues from properties owned.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of employees who perform accounting and bookkeeping functions.

+ References

No definition available.

+ Details

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

- Definition

Represents the amount reimbursed to related party for transfer of employee payroll.

+ References

No definition available.

+ Details

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

- Definition

The aggregate costs of keeping the property in good condition but that do not appreciably prolong the life or increase the value of the property.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_CostOfPropertyRepairsAndMaintenance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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=66011266&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.4)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_GeneralAndAdministrativeExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of cash paid for brokerage fees during the current period. This element is intended to represent the brokerage fees paid by and between financial industry participants.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3536-108585

+ Details

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

- Definition

A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07.2(a),(b),(c),(d))
-URI http://asc.fasb.org/extlink&oid=6488393&loc=d3e606610-122999

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 225
-Section 45
-Paragraph 3
-Subparagraph (k)
-URI http://asc.fasb.org/extlink&oid=6488370&loc=d3e13550-115849

+ Details

Name:	us-gaap_ProfessionalFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionAmountsOfTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nen_HamiltonParkTowersLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nen_PresidentOfManagementCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nen_HaroldBrownMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nen_GeneralPartnerOrManagementCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nen_ManagementCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstatePropertiesAxis=us-gaap_PartiallyOwnedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=nen_ResidentialAndMixedUseRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

RELATED PARTY TRANSACTIONS (Details)	3 Months Ended		6 Months Ended		9 Months Ended		18 Months Ended
RELATED PARTY TRANSACTIONS (Details)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)
RELATED PARTY TRANSACTIONS
Management fee as percentage of gross receipts rental revenue					4.00%
Management fee as a percentage of gross receipts rental revenue of Linewt, LLC					3.00%
Management fees of related party					$ 1,600,000	$ 1,513,000
Management fee	$ 544,399	$ 511,730			1,599,647	1,513,226
Repairs and maintenance	2,678,780	2,364,364			6,187,673	6,185,250
Administrative expense	$ 525,125	$ 524,293			$ 1,513,869	1,477,708
Number of limited partnerships and limited liability companies in which the entity has invested \| item					9
Dexter Park
RELATED PARTY TRANSACTIONS
Management fee as percentage of gross receipts rental revenue					2.00%
President of Management Company
RELATED PARTY TRANSACTIONS
Quarterly fee for asset management consulting services			$ 56,250	$ 56,250
Harold Brown \| Minimum
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	43.20%				43.20%
Harold Brown \| Maximum
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	56.00%				56.00%
General Partner or Management Company [Member]
RELATED PARTY TRANSACTIONS
Repairs and maintenance					$ 199,000
Administrative expense					272,000
Commercial brokerage fees					1,000
Expenses for construction, architectural services and supervision of capital projects					137,000
Costs related to professional services					609,000	772,000
Management Company [Member]
RELATED PARTY TRANSACTIONS
Reimbursement to related party for payroll transfers					$ 2,508,000	$ 2,212,000
Employer contributions in 401K plan			0	0
Number of accounting staff of related party providing bookkeeping and accounting functions \| item					14
Fees for accounting and bookkeeping services			$ 93,750	$ 93,750
Number of employees having ownership interest in the investment properties \| item					6
Fees for accounting and bookkeeping services per year							$ 125,000
Partially owned properties
RELATED PARTY TRANSACTIONS
Management fee as percentage of gross receipts rental revenue					4.00%
Management fee					$ 510,000
Repairs and maintenance					34,000
Administrative expense					27,000
Construction, architectural services and supervision of capital projects					554,000
Amount paid to related party					$ 1,125,000
Residential and mixed-use properties \| Partially owned properties \| Minimum
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	40.00%				40.00%
Residential and mixed-use properties \| Partially owned properties \| Maximum
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	50.00%				50.00%