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INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Details) - 10Q (USD $) | 3 Months Ended | 0 Months Ended | 1 Months Ended | 0 Months Ended | 1 Months Ended | 0 Months Ended | 1 Months Ended | 12 Months Ended | 1 Months Ended |  |  |  |  |  |  |
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Mar. 31, 2015 item | Mar. 31, 2014 | Oct. 18, 2013 | Oct. 28, 2009 | Feb. 28, 2007 | Apr. 30, 2008 item | Mar. 07, 2005 | Sep. 30, 2013 | Mar. 02, 2005 | Oct. 31, 2004 | Jan. 31, 2007 | Aug. 31, 2014 | Dec. 31, 2005 item | Jun. 30, 2013 | Dec. 31, 2014 | Oct. 03, 2005 item | Dec. 31, 2006 | Sep. 30, 2004 item | May 31, 2008 item | Aug. 31, 2004 item | Nov. 30, 2001 item
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of limited partnerships and limited liability companies in which the entity has invested | 9 nen_InvestmentsInNumberOfLimitedPartnershipsAndLimitedLiabilityCompanies |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of partnerships investing in commercial property | 3 nen_NumberOfPartnershipsInvestingInCommercialProperties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments in joint venture | $ 8,268,172 us-gaap_EquityMethodInvestments |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 8,807,868 us-gaap_EquityMethodInvestments |  |  |  |  |  |
Borrowings | 8,076,000 us-gaap_ProceedsFromIssuanceOfDebt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding amount of mortgage loan | 196,038,642 us-gaap_SecuredDebt |  |  |  |  |  |  |  |  |  |  |  |  |  | 196,071,540 us-gaap_SecuredDebt |  |  |  |  |  |
Interest paid | 2,360,000 us-gaap_InterestPaid | 1,664,000 us-gaap_InterestPaid |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Distribution to the Partnership | 951,330 us-gaap_PartnersCapitalAccountDistributions | 969,207 us-gaap_PartnersCapitalAccountDistributions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of investment to discontinue applying the equity method | 0 nen_EquityMethodInvestmentsAmountToDiscontinueApplyingEquityMethodForInvestment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Limited Partnerships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Capital contributions |  |  | 660,000 us-gaap_PartnersCapitalAccountContributions / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_LimitedPartnershipsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dexter Park |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 40.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember | 40.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  | 40.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments in joint venture | 4,302,225 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember | 5,607,127 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  | 15,925,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 409 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember | 409 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  | 409 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase price of investments |  |  |  | 129,500,000 us-gaap_EquityMethodInvestmentAggregateCost / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units retained for long-term investment | 409 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember | 409 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Dexter Park | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings |  |  |  | 89,914,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  | 5.57%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period for which the entity is required to make interest only payments |  |  |  | 2 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization period of debt |  |  |  | 30 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding amount of mortgage loan | 85,897,000 us-gaap_SecuredDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Bay Apartments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |
Investments in joint venture | 916,577 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember | 998,643 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,500,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |
Number of units | 48 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember | 48 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  | 168 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |
Purchase price of investments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 30,875,000 us-gaap_EquityMethodInvestmentAggregateCost / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |
Borrowings |  |  |  |  | 4,750,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  | 5.57%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period for which the entity is required to make interest only payments |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization period of debt |  |  |  |  | 30 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units retained for long-term investment | 48 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember | 48 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  | 48 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |
Number of units sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 120 nen_NumberOfUnitsInRealEstatePropertySold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |
Hamilton Bay Apartments | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding amount of mortgage loan | 4,556,000 us-gaap_SecuredDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Bay Sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments in joint venture | 403,114 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember | 959,932 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 120 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember | 120 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Capital contributions |  |  | 660,000 us-gaap_PartnersCapitalAccountContributions / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units sold | 113 nen_NumberOfUnitsInRealEstatePropertySold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember | 106 nen_NumberOfUnitsInRealEstatePropertySold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Units in Real Estate Property to be Sold | 120 nen_NumberOfUnitsInRealEstatePropertyToBeSold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember | 120 nen_NumberOfUnitsInRealEstatePropertyToBeSold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Bay Sales | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units |  |  |  |  |  | 20 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  | 2,368,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  | 5.75%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Essex Development, LLC and Hamilton Essex 81, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest |  |  |  |  |  |  | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCAndHamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments in joint venture |  |  |  |  |  |  | 2,000,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCAndHamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase price of investments |  |  |  |  |  |  | 14,300,000 us-gaap_EquityMethodInvestmentAggregateCost / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCAndHamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Essex Development, LLC and Hamilton Essex 81, LLC | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  | 10,750,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCAndHamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Essex 81 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments in joint venture | 321,028 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember | 261,162 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 49 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember | 49 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  | 48 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties |  |  |  |  |  |  | 1 us-gaap_NumberOfRealEstateProperties / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units retained for long-term investment | 49 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember | 49 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Essex 81 | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings | 8,076,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) | 5.79%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization period of debt | 30 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Essex Development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investments in joint venture | 347,460 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember | 331,618 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 1 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember | 1 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units retained for long-term investment | 1 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember | 1 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Capacity of real estate property (in cars per lot) |  |  |  |  |  |  | 50 nen_CapacityOfRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Essex Development | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings | 1,975,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contractual principal payments to be made |  |  |  |  |  |  |  | 4,443 us-gaap_DebtInstrumentPeriodicPaymentPrincipal / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |
Margin over basis of interest rate (as a percent) | 2.25%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis of interest rate | Libor |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Notional margin over basis of interest rate (as a percent) | 0.171%nen_DebtInstrumentNotionalBasisSpreadOnVariableRate / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cost associated with loan extension |  |  |  |  |  |  |  | 9,000 nen_DebtInstrumentCostOfExtensionOfLoan / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |
Extended term of debt |  |  |  |  |  |  |  | 2 years |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum personal guaranty on mortgage |  |  |  |  |  |  |  | 1,000,000 us-gaap_GuaranteeObligationsMaximumExposure / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 2.25%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton 1025 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |
Investments in joint venture | 181,023 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember | 249,171 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  | 2,352,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 176 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember | 176 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  | 176 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |
Purchase price of investments |  |  |  |  |  |  |  |  | 23,750,000 us-gaap_EquityMethodInvestmentAggregateCost / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |
Number of units retained for long-term investment | 49 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember | 49 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  | 49 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |
Number of units sold | 127 nen_NumberOfUnitsInRealEstatePropertySold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember | 127 nen_NumberOfUnitsInRealEstatePropertySold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  | 127 nen_NumberOfUnitsInRealEstatePropertySold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |
Number of Units in Real Estate Property to be Sold | 127 nen_NumberOfUnitsInRealEstatePropertyToBeSold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember | 127 nen_NumberOfUnitsInRealEstatePropertyToBeSold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Hamilton 1025 | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  | 5,000,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  |  |  |  | 5.67%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |
Period for which the entity is required to make interest only payments |  |  |  |  |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |  |  |
Amortization period of debt |  |  |  |  |  |  |  |  | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Outstanding amount of mortgage loan | 4,787,000 us-gaap_SecuredDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of debt |  |  |  |  |  |  |  |  | 10 years |  |  |  |  |  |  |  |  |  |  |  |
Hamilton Minuteman |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |
Investments in joint venture | 601,920 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember | 690,012 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,075,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |
Number of units | 42 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember | 42 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 42 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |
Purchase price of investments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,100,000 us-gaap_EquityMethodInvestmentAggregateCost / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |
Number of units retained for long-term investment | 42 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember | 42 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount returned to partnership |  |  |  |  |  |  |  |  |  | 3,775,000 us-gaap_ProceedsFromRepaymentsOfDebtMaturingInMoreThanThreeMonths / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |  |
Cash contribution by the entity towards loan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,250,000 nen_DebtInstrumentCashContributionByEntityTowardsDebt / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |
Hamilton Minuteman | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |  | 8,025,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember | 5,500,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  |  |  |  |  |  | 5.67%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |
Period for which the entity is required to make interest only payments |  |  |  |  |  |  |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |
Amortization period of debt |  |  |  |  |  |  |  |  |  |  | 30 years |  |  |  |  |  |  |  |  |  |
Outstanding amount of mortgage loan | 5,272,000 us-gaap_SecuredDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of debt |  |  |  |  |  |  |  |  |  |  | 10 years |  |  |  |  |  |  |  |  |  |
Hamilton on Main Apts |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |
Investments in joint venture | 1,194,825 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember | 2,534,676 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,000,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |
Number of units | 148 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember | 148 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 280 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |
Purchase price of investments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 56,000,000 us-gaap_EquityMethodInvestmentAggregateCost / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |
Number of units retained for long-term investment | 148 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember | 148 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 137 nen_NumberOfUnitsInRealEstatePropertySold / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |  |
Hamilton on Main Apartments, LLC | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties |  |  |  |  |  |  |  |  |  |  |  |  | 3 us-gaap_NumberOfRealEstateProperties / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |  |  |  | 16,900,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember | 16,825,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  |  |  |  |  |  |  | 4.34%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember | 5.18%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember |  |  |  |  |  |  |  |
Period for which the entity is required to make interest only payments |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |
Amortization period of debt |  |  |  |  |  |  |  |  |  |  |  |  | 30 years |  |  |  |  |  |  |  |
Term of debt |  |  |  |  |  |  |  |  |  |  |  | 10 years | 10 years |  |  |  |  |  |  |  |
Cost associated with loan extension |  |  |  |  |  |  |  |  |  |  |  | 161,000 nen_DebtInstrumentCostOfExtensionOfLoan / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember |  |  |  |  |  |  |  |  |
Term excluding period for which interest only payments to be made |  |  |  |  |  |  |  |  |  |  |  |  | 7 years |  |  |  |  |  |  |  |
Net proceeds after funding escrow accounts and closing costs |  |  |  |  |  |  |  |  |  |  |  |  | 16,700,000 us-gaap_ProceedsFromDebtNetOfIssuanceCosts / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember |  |  |  |  |  |  |  |
Debt Instrument, Loan Proceeds Utilized to Pay Off Existing Mortgage |  |  |  |  |  |  |  |  |  |  |  | 15,205,000 nen_DebtInstrumentLoanProceedsUtilizedToPayOffExistingMortgage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember |  |  |  |  |  |  |  |  |
Debt Instrument, Loan Proceeds distributed to the Partnership |  |  |  |  |  |  |  |  |  |  |  | 850,000 nen_Nen_DebtInstrumentLoanProceedsDistributedToPartnership / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainApartmentsLLCMember |  |  |  |  |  |  |  |  |
345 Franklin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember
Investments in joint venture |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,533,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember
Number of units | 40 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember | 40 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 40 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember
Number of units retained for long-term investment | 40 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember | 40 nen_NumberOfUnitsInRealEstatePropertyRetainedForLongTermInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Distribution to the Partnership |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,610,000 us-gaap_PartnersCapitalAccountDistributions / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |
Carrying value of investment to discontinue applying the equity method |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 nen_EquityMethodInvestmentsAmountToDiscontinueApplyingEquityMethodForInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |
345 Franklin | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Borrowings |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000 us-gaap_ProceedsFromIssuanceOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.87%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |
Period for which the entity is required to make interest only payments |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |
Amortization period of debt |  |  |  |  |  |  |  |  |  |  |  |  |  | 30 years |  |  |  |  |  |  |
Outstanding amount of mortgage loan | 10,000,000 us-gaap_SecuredDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of debt |  |  |  |  |  |  |  |  |  |  |  |  |  | 15 years |  |  |  |  |  |  |
Repayment of loan |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 6,776,000 us-gaap_RepaymentsOfDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |
Residential buildings | Dexter Park |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 409 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember | 409 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonParkTowersLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Residential buildings | Hamilton Bay Apartments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 48 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember | 48 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayApartmentsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Residential buildings | Hamilton Bay Sales |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 120 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember | 120 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonBayLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Residential buildings | Hamilton Essex 81 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 48 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember | 48 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Residential buildings | Hamilton 1025 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 175 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember | 175 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Residential buildings | Hamilton Minuteman |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 42 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember | 42 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonMinutemanLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Residential buildings | Hamilton on Main Apts |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 148 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember | 148 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonOnMainLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Residential buildings | 345 Franklin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 40 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember | 40 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ResidentialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Franklin345LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commercial | Hamilton Essex 81 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 1 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_CommercialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember | 1 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_CommercialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssex81LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commercial | Hamilton Essex Development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 1 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_CommercialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember | 1 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_CommercialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_HamiltonEssexDevelopmentLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commercial | Hamilton 1025 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of units | 1 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_CommercialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember | 1 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_CommercialRealEstateMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_Hamilton1025LLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management Company |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of employees having ownership interest in the investment properties | 6 nen_NumberOfEmployeesHavingOwnershipInterest / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = nen_ManagementCompanyMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) | 3.76%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum | Limited Partnerships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 40.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_LimitedPartnershipsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum | Harold Brown |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 43.20%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = nen_HaroldBrownMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | Mortgages payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest rate (as a percent) | 5.97%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_MortgagesMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | Limited Partnerships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = nen_LimitedPartnershipsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | Harold Brown |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership interest | 57.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = nen_HaroldBrownMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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- Definition Represents the capacity of real estate property. + References No definition available. + Details
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- Definition Represents the amortization period of mortgage loan and its interest. + References No definition available. + Details
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- Definition Represents the cash contribution by the entity towards the debt. + References No definition available. + Details
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- Definition Represents the cost associated with the extension of mortgage loan. + References No definition available. + Details
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- Definition Represents the extended term of mortgage loan. + References No definition available. + Details
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- Definition Represents the amount of loan proceeds utilized for paying off the existing mortgage. + References No definition available. + Details
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- Definition The notional percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
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- Definition Represents the term excluding period for which interest only payments are to be made. + References No definition available. + Details
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- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
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- Definition The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR. + References No definition available. + Details
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Amount of the required periodic payments applied to principal. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 + Details
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- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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