Number of persons employed by the Entity

No definition available.

Name:	dei_EntityNumberOfEmployees
Namespace Prefix:	dei_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- 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 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:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Cost of labor directly related to good produced and service rendered. Includes, but is not limited to, payroll cost and equity-based compensation.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

+ Details

Name:	us-gaap_CostDirectLabor
Namespace Prefix:	us-gaap_
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://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

+ Details

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

- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

+ 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/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types: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

+ Details

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

- Definition

The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

+ Details

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

- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479041/842-20-45-4

+ Details

Name:	us-gaap_OperatingLeaseExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480167/946-830-55-10

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Subparagraph (k)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483581/946-220-45-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

+ Details

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

- Definition

The percentage charged for managing real estate properties.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyManagementFeePercentFee
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of revenue derived from managing real estate properties.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyManagementFeeRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

+ Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=nen_BrownFamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=nen_NewEnglandRealtyAssociatesLimitedPartnership40PercentOwnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=nen_NewEnglandRealtyAssociatesLimitedPartnership50PercentOwnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=nen_MajorityOfPartnershipPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=nen_HamiltonLinewtLLCCommercial1031ExchangeNewtonMassachusettsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=nen_GeneralPartnerOrManagementCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=nen_HamiltonCompanyIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_ManagementServiceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_ConstructionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_MaintenanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nen_LegalExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nen_RentingExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=nen_HamiltonParkTowersLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=nen_SallyMichaelMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=nen_CurrentAndFormerManagementCompanyEmployeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

RELATED PARTY TRANSACTIONS (Details)	3 Months Ended		9 Months Ended		12 Months Ended
RELATED PARTY TRANSACTIONS (Details)	Sep. 30, 2023 USD ($) item	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) item	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Aug. 23, 2023
RELATED PARTY TRANSACTIONS
Management fee	$ 810,436	$ 683,999	$ 2,173,272	$ 2,029,453
Repairs and maintenance	3,611,652	3,126,953	9,853,498	8,381,339
Administrative expense	642,907	696,656	2,247,729	2,028,319
Renting	$ 391,093	$ 181,574	827,112	$ 501,906
Employer contributions in 401K plan			$ 48,000
Number of limited partnerships and limited liability companies in which the entity has invested \| item			7
Brown Family \| Minimum
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	47.60%		47.60%
Brown Family \| Maximum
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	59.00%		59.00%
Brown Family \| Related party \| Minimum
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	47.60%		47.60%
Brown Family \| Related party \| Maximum
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	59.00%		59.00%
NERA 40%
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	40.00%	40.00%	40.00%	40.00%
NERA 50%
RELATED PARTY TRANSACTIONS
Ownership interest (as a percent)	50.00%	50.00%	50.00%	50.00%		50.00%
Majority of Partnership Properties \| Related party
RELATED PARTY TRANSACTIONS
Management fee as percentage of gross receipts rental revenue			4.00%
Management fee (as a percent)			4.00%
Linewt \| Related party
RELATED PARTY TRANSACTIONS
Management fee as percentage of gross receipts rental revenue			3.00%
General Partner or Management Company \| Related party
RELATED PARTY TRANSACTIONS
Costs related to professional services			$ 1,106,000	$ 583,000
Repairs and maintenance			184,000
Administrative expense			293,000
Renting			66,000
Construction, architectural services and supervision of capital projects			563,000
Hamilton Company/Management Company \| Related party
RELATED PARTY TRANSACTIONS
Management fee			2,173,000	2,029,000
Costs related to professional services			93,750	93,750	$ 125,000
Amount received for management fees			585,000
Payroll and related expenses			3,210,000	2,945,000
Employer contributions in 401K plan			$ 48,000	70,000
Number of accounting staff providing bookkeeping and accounting functions \| item	15		15
Hamilton Company/Management Company \| Management fee \| Related party
RELATED PARTY TRANSACTIONS
Amount received for management fees			$ 514,000
Hamilton Company/Management Company \| Construction, architectural services and supervision of capital projects \| Related party
RELATED PARTY TRANSACTIONS
Amount received for management fees			5,000
Hamilton Company/Management Company \| Repairs and maintenance \| Related party
RELATED PARTY TRANSACTIONS
Amount received for management fees			43,000
Hamilton Company/Management Company \| Legal expense \| Related party
RELATED PARTY TRANSACTIONS
Amount received for management fees			22,000
Hamilton Company/Management Company \| Renting Expense [Member] \| Related party
RELATED PARTY TRANSACTIONS
Amount received for management fees			$ 1,000
Dexter Park \| Related party
RELATED PARTY TRANSACTIONS
Management fee (as a percent)			2.00%
Sally Michael \| Related party
RELATED PARTY TRANSACTIONS
Legal fees			$ 80,000	$ 68,000
Current and previous management company employees \| Related party
RELATED PARTY TRANSACTIONS
Number of employees having ownership interest in the investment properties \| item			5