Name:	dei_EntityListingDepositoryReceiptRatio
Namespace Prefix:	dei_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

Represents the number of depository receipts repurchased under the equity repurchase program.

No definition available.

Name:	nen_PartnersCapitalAccountDepositoryReceiptsTreasury
Namespace Prefix:	nen_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Represents the average price at which depository receipts are repurchased under the equity repurchase program.

No definition available.

Name:	nen_PartnersCapitalAccountDepositoryReceiptsTreasuryAverageRepurchasePricePerDepositoryReceipt
Namespace Prefix:	nen_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Represents the number of depository receipts authorized to be repurchased under the equity repurchase program.

No definition available.

Name:	nen_PartnersCapitalAccountDepositoryReceiptsTreasuryReceiptsAuthorizedToBeRepurchased
Namespace Prefix:	nen_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Represents the fixed distribution percentages of the holders of units based on which the entity is required to purchase the proportionate number of specific units with every purchase of depository receipts.

No definition available.

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

Represents the percentage of issued and outstanding units owned by the partners.

No definition available.

Name:	nen_PartnersCapitalAccountPercentageOfIssuedAndOutstandingUnitsOwnedByPartners
Namespace Prefix:	nen_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the period over which the entity is permitted to purchase its depository receipts.

No definition available.

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

Represents the number of treasury units outstanding as on the balance sheet date.

No definition available.

Name:	nen_PartnersCapitalAccountTreasuryUnitsIssued
Namespace Prefix:	nen_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Represents the average price at which units are repurchased under the equity repurchase program.

No definition available.

Name:	nen_PartnersCapitalAccountUnitsTreasuryAverageRepurchasePricePerUnit
Namespace Prefix:	nen_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Value of units that were previously issued and have been repurchased during the year.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 272

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6828210&loc=d3e70191-108054

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Practice Bulletin (PB)

-Number 14

-Paragraph 8

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

Units that were previously issued and have been repurchased during the year.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 5

-Subparagraph (SAB TOPIC 4.F)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187171-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Practice Bulletin (PB)

-Number 14

-Paragraph 15

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_PartnersCapitalAccountUnitsTreasury
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Units that were previously issued and then were repurchased and classified as treasury units. This element represents the number of these units which were reissued during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770