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v2.4.1.9

TREASURY UNITS (Details) (USD $) | 0 Months Ended | 12 Months Ended | 76 Months Ended | 88 Months Ended | 2 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Aug. 08, 2008 | Aug. 20, 2007 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2013 | Dec. 31, 2014 | Dec. 31, 2014 | Mar. 10, 2015 | Mar. 06, 2008 | Jan. 30, 2008 | Jan. 15, 2008 | Jan. 03, 2012
Treasury units |  |  | 52,572 nen_PartnersCapitalAccountTreasuryUnitsIssued |  |  |  | 52,572 nen_PartnersCapitalAccountTreasuryUnitsIssued | 52,572 nen_PartnersCapitalAccountTreasuryUnitsIssued |  |  |  |  |
Period for repurchase of depository receipts | 12 months | 12 months |  |  |  |  |  |  |  |  |  |  |
Depository receipts authorized to be repurchased |  | 300,000 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryReceiptsAuthorizedToBeRepurchased |  |  |  |  |  |  | 2,000,000 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryReceiptsAuthorizedToBeRepurchased | 1,500,000 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryReceiptsAuthorizedToBeRepurchased | 900,000 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryReceiptsAuthorizedToBeRepurchased | 600,000 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryReceiptsAuthorizedToBeRepurchased |
Repurchase of depository receipts |  |  | 44,025 nen_PartnersCapitalAccountDepositoryReceiptsTreasury | 22,964 nen_PartnersCapitalAccountDepositoryReceiptsTreasury |  | 1,286,916 nen_PartnersCapitalAccountDepositoryReceiptsTreasury |  | 1,286,916 nen_PartnersCapitalAccountDepositoryReceiptsTreasury |  |  |  |  |
Repurchase price of depository receipts |  |  | $ 47.90 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryAverageRepurchasePricePerDepositoryReceipt | $ 37.80 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryAverageRepurchasePricePerDepositoryReceipt |  |  | $ 25.65 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryAverageRepurchasePricePerDepositoryReceipt |  |  |  |  |  |
Repurchase price of units |  |  | $ 1,437 nen_PartnersCapitalAccountUnitsTreasuryAverageRepurchasePricePerUnit | $ 1,134 nen_PartnersCapitalAccountUnitsTreasuryAverageRepurchasePricePerUnit |  |  |  |  |  |  |  |  |
Repurchase of units |  |  | 1,834 us-gaap_PartnersCapitalAccountUnitsTreasury | 957 us-gaap_PartnersCapitalAccountUnitsTreasury | 1,040 us-gaap_PartnersCapitalAccountUnitsTreasury |  |  |  |  |  |  |  |
Total cost of repurchase |  |  | $ 2,685,583 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases | $ 1,094,609 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases | $ 906,214 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases |  | $ 35,167,000 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases |  |  |  |  |  |
Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of depository receipts |  |  |  |  |  |  |  |  | 19,415 nen_PartnersCapitalAccountDepositoryReceiptsTreasury / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |
Repurchase price of depository receipts |  |  |  |  |  |  |  |  | $ 50.00 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryAverageRepurchasePricePerDepositoryReceipt / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |
Repurchase price of units |  |  |  |  |  |  |  |  | $ 1,500.00 nen_PartnersCapitalAccountUnitsTreasuryAverageRepurchasePricePerUnit / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |
Repurchase of depository receipts |  |  |  |  |  |  |  |  | 975,731 nen_PartnersCapitalAccountDepositoryReceiptsTreasuryRepurchased / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |
Class A |  |  |  |  |  |  |  |  |  |  |  |  |
Treasury units |  |  | 42,057 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember |  |  |  | 42,057 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember | 42,057 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember |  |  |  |  |
Number of units in each depository receipt |  | 0.1 dei_EntityListingDepositoryReceiptRatio / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember |  |  |  |  |  |  |  |  |  |  | 0.03333 dei_EntityListingDepositoryReceiptRatio / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember
Fixed distribution percentage of unit holders |  |  | 80.00%nen_PartnersCapitalAccountFixedDistributionPercentageOfHoldersOfUnits / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember |  |  |  |  |  |  |  |  |  |
Repurchase price of units |  |  |  |  |  |  | $ 769.50 nen_PartnersCapitalAccountUnitsTreasuryAverageRepurchasePricePerUnit / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember |  |  |  |  |  |
Total cost of repurchase |  |  | 2,158,332 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember | 877,623 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember | 726,058 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassAMember |  |  |  |  |  |  |  |
Class B |  |  |  |  |  |  |  |  |  |  |  |  |
Treasury units |  |  | 9,989 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember |  |  |  | 9,989 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember | 9,989 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember |  |  |  |  |
Fixed distribution percentage of unit holders |  |  | 19.00%nen_PartnersCapitalAccountFixedDistributionPercentageOfHoldersOfUnits / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember |  |  |  |  |  |  |  |  |  |
Repurchase of depository receipts |  |  |  |  |  |  | 2,452 nen_PartnersCapitalAccountDepositoryReceiptsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember |  |  |  |  |  |
Repurchase price of units |  |  |  |  |  |  | $ 769.53 nen_PartnersCapitalAccountUnitsTreasuryAverageRepurchasePricePerUnit / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember |  |  |  |  |  |
Repurchase of units |  |  | 349 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember | 182 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember |  |  | 2,452 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember |  |  |  |  |  |
Total cost of repurchase |  |  | 500,888 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember | 206,137 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember | 171,148 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember |  |  |  |  |  |  |  |
Class B | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of units |  |  |  |  |  |  |  |  | 154 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |
Total cost of repurchase |  |  |  |  |  |  |  |  | 230,574 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = nen_LimitedClassBMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |
General Partnership |  |  |  |  |  |  |  |  |  |  |  |  |
Treasury units |  |  | 526 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember |  |  |  | 526 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember | 526 nen_PartnersCapitalAccountTreasuryUnitsIssued / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember |  |  |  |  |
Fixed distribution percentage of unit holders |  |  | 1.00%nen_PartnersCapitalAccountFixedDistributionPercentageOfHoldersOfUnits / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember |  |  |  |  |  |  |  |  |  |
Repurchase price of units |  |  |  |  |  |  | $ 769.53 nen_PartnersCapitalAccountUnitsTreasuryAverageRepurchasePricePerUnit / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember |  |  |  |  |  |
Repurchase of units |  |  | 18 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember | 10 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember |  | 129 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember | 129 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember |  |  |  |  |  |
Total cost of repurchase |  |  | 26,363 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember | 10,849 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember | 9,008 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember |  |  |  |  |  |  |  |
General Partnership | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of units |  |  |  |  |  |  |  |  | 8 us-gaap_PartnersCapitalAccountUnitsTreasury / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |
Total cost of repurchase |  |  |  |  |  |  |  |  | $ 12,135 us-gaap_PartnersCapitalAccountTreasuryUnitsPurchases / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_GeneralPartnerMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |

X
- Definition The number of underlying shares represented by one American Depository Receipt (ADR) or Global Depository Receipt (GDR). A value of "3" means that one ADR represents 3 underlying shares. If one underlying share represents 2 ADR's then the value would be represented as "0.5". + References No definition available. + Details
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- Definition Represents the number of depository receipts repurchased under the equity repurchase program. + References No definition available. + Details
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- Definition Represents the average price at which depository receipts are repurchased under the equity repurchase program. + References No definition available. + Details
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- Definition Represents the number of depository receipts authorized to be repurchased under the equity repurchase program. + References No definition available. + Details
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- Definition 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. + References No definition available. + Details
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- Definition Represents the period over which the entity is permitted to purchase its depository receipts. + References No definition available. + Details
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- Definition Represents the number of treasury units outstanding as on the balance sheet date. + References No definition available. + Details
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- Definition Represents the average price at which units are repurchased under the equity repurchase program. + References No definition available. + Details
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X
- Definition Value of units that were previously issued and have been repurchased during the year. + References 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 + Details
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- Definition Units that were previously issued and have been repurchased during the year. + References 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=27012166&loc=d3e187171-122770 + Details
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