Area of a real estate property sold.

No definition available.

Name:	nen_AreaOfRealEstatePropertySold
Namespace Prefix:	nen_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the closing costs associated with the transaction.

+ References

No definition available.

+ Details

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

- Definition

The number of real estate property purchased.

+ References

No definition available.

+ Details

Name:	nen_NumberOfRealEstatePropertiesPurchased
Namespace Prefix:	nen_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	nen_NumberOfRealEstatePropertiesSold
Namespace Prefix:	nen_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the amortization period of value of the in-place leases.

+ References

No definition available.

+ Details

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

- Definition

Represents the aggregate purchase price of real estate properties acquired by the entity.

+ References

No definition available.

+ Details

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

- Definition

Represents the aggregate purchase price of real estate properties acquired by the entity allocated to below-market leases.

+ References

No definition available.

+ Details

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

- Definition

Represents the aggregate purchase price of real estate properties acquired by the entity allocated to leases.

+ References

No definition available.

+ Details

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

- Definition

Represents the aggregate purchase price of real estate properties acquired by the entity allocated to tenant relationships.

+ References

No definition available.

+ Details

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

- Definition

Amount of real estate property purchase price payment financed through borrowings under master credit facility.

+ References

No definition available.

+ Details

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

- Definition

Amount of real estate property purchase price payment financed through interim loan.

+ References

No definition available.

+ Details

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

- Definition

Represents the amortization period of value of the tenant relationships.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482949/835-30-55-8

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69B

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69C

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482900/835-30-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482925/835-30-45-2

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

+ Details

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

- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-12

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=nen_MasterCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_PropertiesAtBelmontMassachusettsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_MixedUsePropertiesInBelmontMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=us-gaap_ResidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=nen_CommercialOfficeBuildingsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_CommercialPropertiesInBelmontMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_PropertiesAtBrightonAndConcordAvenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

RENTAL PROPERTIES - Belmont Acquisition (Details)	Jan. 28, 2026 USD ($) ft² building	Jun. 18, 2025 USD ($) building item	Dec. 31, 2025 USD ($)	Jun. 16, 2022 USD ($)	Nov. 30, 2021 USD ($)
Facility Agreement
RENTAL PROPERTIES
Loan amount				$ 80,284,000	$ 156,000,000
Belmont Massachusetts property
RENTAL PROPERTIES
Borrowings used for purchase of property		$ 40,000,000
Loan for purchase of property		67,500,000
Belmont Massachusetts property \| Facility Agreement
RENTAL PROPERTIES
Loan amount			$ 67,656,000
Mixed use property
RENTAL PROPERTIES
Purchase price of real estate properties		175,000,000
Closing costs		$ 218,000
Mixed use property \| Residential
RENTAL PROPERTIES
Number of real estate property purchased \| item		396
Mixed use property \| Commercial Office Buildings
RENTAL PROPERTIES
Number of real estate property purchased \| building		2
Commercial property \| Commercial Office Buildings \| Subsequent Event
RENTAL PROPERTIES
Number of real estate properties sold \| building	2
Area of real estate property sold (in square feet) \| ft²	14,000
Properties sold	$ 2,600,000
Loss on sale of properties	$ (400,000)
Properties at Brighton and Concord Avenue \| Commercial
RENTAL PROPERTIES
Purchase price allocated to the value of the in-place leases		$ 4,714,000
Purchase price allocated to the value of the tenant relationships		305,000
Purchase price allocated to the value of below market leases		$ 1,165,000
Amortization period of value of the in-place leases		12 months
Amortization period of value of the tenant relationships		36 months