XML 72 R41.htm IDEA: XBRL DOCUMENT
v3.3.1.900

RENTAL PROPERTIES (Real estate) (Details) - USD ($) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Gross Amount at Which Carried at Close of Period |  |  |  |
Totals | $ 261,276,898 | $ 225,021,946 | $ 221,454,286 | $ 158,624,893
Accumulated Depreciation | $ 84,579,584 | $ 75,905,862 | $ 68,549,625 | $ 63,651,293
Buildings and improvements | Minimum |  |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Estimated useful lives | 10 years |  |  |
Buildings and improvements | Maximum |  |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Estimated useful lives | 39 years |  |  |
Other Categories of Assets | Minimum |  |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Estimated useful lives | 5 years |  |  |
Other Categories of Assets | Maximum |  |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Estimated useful lives | 15 years |  |  |
Boylston Downtown L.P. Residential Apartments Boston, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | $ 40,000,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 2,112,000 |  |  |
Building Improvements | 8,593,109 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 8,192,079 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 2,112,000 |  |  |
Building Improvements | 16,785,188 |  |  |
Totals | 18,897,188 |  |  |
Accumulated Depreciation | 10,755,089 |  |  |
Brookside Associates LLC Residential Apartments Woburn, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 2,598,337 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 684,000 |  |  |
Building Improvements | 3,116,000 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 432,302 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 684,000 |  |  |
Building Improvements | 3,548,302 |  |  |
Totals | 4,232,302 |  |  |
Accumulated Depreciation | 1,945,022 |  |  |
Clovelly Apartments L.P. Residential Apartments Nashua, New Hampshire |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 4,160,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 177,610 |  |  |
Building Improvements | 1,478,359 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 1,689,128 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 177,610 |  |  |
Building Improvements | 3,167,487 |  |  |
Totals | 3,345,097 |  |  |
Accumulated Depreciation | 2,154,856 |  |  |
Commonwealth 1137 L.P. Residential Apartments Boston, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 3,750,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 342,000 |  |  |
Building Improvements | 1,367,669 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 1,196,696 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 342,000 |  |  |
Building Improvements | 2,564,365 |  |  |
Totals | 2,906,365 |  |  |
Accumulated Depreciation | 1,532,004 |  |  |
Commonwealth 1144 L.P. Residential Apartments Boston, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 14,780,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 1,410,000 |  |  |
Building Improvements | 5,664,816 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 2,207,782 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 1,410,000 |  |  |
Building Improvements | 7,872,598 |  |  |
Totals | 9,282,598 |  |  |
Accumulated Depreciation | 5,199,814 |  |  |
Executive Apartments L.P. Residential Apartments Framingham, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 2,415,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 91,400 |  |  |
Building Improvements | 740,360 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 1,226,670 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 91,400 |  |  |
Building Improvements | 1,967,030 |  |  |
Totals | 2,058,430 |  |  |
Accumulated Depreciation | 1,062,137 |  |  |
Hamilton Battle Green LLC Residential Apartments Lexington, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 4,649,132 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 1,341,737 |  |  |
Building Improvements | 8,457,497 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 170,445 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 1,341,737 |  |  |
Building Improvements | 8,627,942 |  |  |
Totals | 9,969,679 |  |  |
Accumulated Depreciation | 1,823,135 |  |  |
Hamilton Cypress LLC Commercial-1031Exchange Brookline, Massachusetts |  |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 2,362,596 |  |  |
Building Improvements | 4,613,985 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 259,375 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 2,362,596 |  |  |
Building Improvements | 4,873,360 |  |  |
Totals | 7,235,956 |  |  |
Accumulated Depreciation | 1,085,242 |  |  |
Hamilton Green Apartments Residential Apartments Andover, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 38,500,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 16,054,336 |  |  |
Building Improvements | 44,794,438 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 748,572 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 16,054,336 |  |  |
Building Improvements | 45,543,010 |  |  |
Totals | 61,597,346 |  |  |
Accumulated Depreciation | 8,395,786 |  |  |
Hamilton Linewt LLC Commercial-1031 Exchange Newton, Massachusetts |  |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 884,042 |  |  |
Building Improvements | 2,652,127 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 62,608 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 884,042 |  |  |
Building Improvements | 2,714,735 |  |  |
Totals | 3,598,777 |  |  |
Accumulated Depreciation | 564,048 |  |  |
Hamilton Oaks Associates LLC Residential Apartments Brockton, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 11,925,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 2,175,000 |  |  |
Building Improvements | 12,325,000 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 2,574,848 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 2,175,000 |  |  |
Building Improvements | 14,899,848 |  |  |
Totals | 17,074,848 |  |  |
Accumulated Depreciation | 8,580,806 |  |  |
Highland Street Apartments, L.P. Residential Apartments Lowell, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 1,050,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 156,000 |  |  |
Building Improvements | 634,085 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 338,724 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 156,000 |  |  |
Building Improvements | 972,809 |  |  |
Totals | 1,128,809 |  |  |
Accumulated Depreciation | 635,675 |  |  |
Linhart L.P. Residential/Commercial Newton, Massachusetts |  |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 385,000 |  |  |
Building Improvements | 1,540,000 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 1,331,870 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 385,000 |  |  |
Building Improvements | 2,871,870 |  |  |
Totals | 3,256,870 |  |  |
Accumulated Depreciation | 2,047,890 |  |  |
NERA Dean St. Associates LLC Residential Apartments Norwood, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 5,687,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 1,512,000 |  |  |
Building Improvements | 5,701,480 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 961,065 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 1,512,000 |  |  |
Building Improvements | 6,662,545 |  |  |
Totals | 8,174,545 |  |  |
Accumulated Depreciation | 3,143,032 |  |  |
North Beacon 140 L.P. Residential Units Boston, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 6,937,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 936,000 |  |  |
Building Improvements | 3,762,013 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 2,158,122 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 936,000 |  |  |
Building Improvements | 5,920,135 |  |  |
Totals | 6,856,135 |  |  |
Accumulated Depreciation | 3,743,872 |  |  |
Olde English Apartments L.P. Residential Apartments Lowell, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 3,080,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 46,181 |  |  |
Building Improvements | 878,323 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 1,262,126 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 46,181 |  |  |
Building Improvements | 2,140,449 |  |  |
Totals | 2,186,630 |  |  |
Accumulated Depreciation | 1,386,246 |  |  |
Redwood Hills L.P. Residential Units Worcester, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 6,743,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 1,200,000 |  |  |
Building Improvements | 4,810,604 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 3,171,266 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 1,200,000 |  |  |
Building Improvements | 7,981,870 |  |  |
Totals | 9,181,870 |  |  |
Accumulated Depreciation | 4,753,632 |  |  |
Residences at CaptainParkers LLC Residential Apartments Lexington, Massachusetts |  |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 6,247,153 |  |  |
Building Improvements | 24,954,777 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 31,201,930 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 6,247,153 |  |  |
Building Improvements | 24,954,777 |  |  |
Totals | 31,201,930 |  |  |
Accumulated Depreciation | 385,301 |  |  |
River Drive L.P. Residential Apartments Danvers, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 3,465,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 72,525 |  |  |
Building Improvements | 587,777 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 1,130,773 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 72,525 |  |  |
Building Improvements | 1,718,550 |  |  |
Totals | 1,791,075 |  |  |
Accumulated Depreciation | 847,593 |  |  |
Riverside Apartments Condominium Units Massachusetts |  |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 23,346 |  |  |
Building Improvements | 190,807 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 54,973 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 23,346 |  |  |
Building Improvements | 245,780 |  |  |
Totals | 269,126 |  |  |
Accumulated Depreciation | 205,387 |  |  |
School St Assoc LLC Residential Apartments Framingham, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 15,000,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 4,686,728 |  |  |
Building Improvements | 18,746,911 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | (1,254,212) |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 4,686,728 |  |  |
Building Improvements | 17,492,699 |  |  |
Totals | 22,179,427 |  |  |
Accumulated Depreciation | 7,958,005 |  |  |
WRF Associates LLC Strip Mall Framingham, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 6,000,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 3,280,000 |  |  |
Building Improvements | 4,920,000 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 86,445 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 3,280,000 |  |  |
Building Improvements | 5,006,445 |  |  |
Totals | 8,286,445 |  |  |
Accumulated Depreciation | 2,737,573 |  |  |
WCB Associates LLC Residential Apartments Brockton, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 7,000,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 1,335,000 |  |  |
Building Improvements | 7,565,501 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 1,722,213 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 1,335,000 |  |  |
Building Improvements | 9,287,714 |  |  |
Totals | 10,622,714 |  |  |
Accumulated Depreciation | 5,303,172 |  |  |
Westgate Apartments Residential Units Burlington Massachusetts Member |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 2,500,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 44,965 |  |  |
Building Improvements | 4,478,687 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 244,281 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 44,965 |  |  |
Building Improvements | 4,722,968 |  |  |
Totals | 4,767,933 |  |  |
Accumulated Depreciation | 1,984,655 |  |  |
Westgate Apartments LLC Residential Apartments Woburn, Massachusetts |  |  |  |
Real estate and accumulated depreciation |  |  |  |
Encumbrances (First Mortgages) | 15,700,000 |  |  |
Initial Cost to Partnerships |  |  |  |
Land | 461,300 |  |  |
Building Improvements | 2,424,636 |  |  |
Cost Capitalized Subsequent to Acquisition |  |  |  |
Improvements, Net of retirements | 8,333,060 |  |  |
Gross Amount at Which Carried at Close of Period |  |  |  |
Land | 417,107 |  |  |
Building Improvements | 10,757,696 |  |  |
Totals | 11,174,803 |  |  |
Accumulated Depreciation | $ 6,349,611 |  |  |

X
- References No definition available. + Details
Name: | nen_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionAbstract
Namespace Prefix: | nen_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of land and buildings and improvements made to real estate investments and capitalized after acquisition for entities with a substantial portion of business acquiring and holding investment real estate , net of retirements. + References No definition available. + Details
Name: | nen_SecScheduleIiiRealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionImprovementsNetOfRetirements
Namespace Prefix: | nen_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated depreciation pertaining to real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of lien or mortgage outstanding on real estate investment properties for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before accumulated depreciation of buildings and improvements for entities with a substantial portion of business acquiring and holding investment real estate. Excludes real estate not held as an investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of land for entities with a substantial portion of business acquiring and holding investment real estate. Excludes real estate not held as an investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Initial cost of buildings and improvements for entities with a substantial portion of business acquiring and holding investment real estate. Excludes real estate not held as an investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Initial cost of land for entities with a substantial portion of business acquiring and holding investment real estate. Excludes real estate not held as an investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Useful life on which depreciation was computed for entities with a substantial portion of business acquiring and holding investment real estate, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationLifeUsedForDepreciation1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- 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_RealEstateAndAccumulatedDepreciationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before accumulated depreciation, of real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateGrossAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_PropertySubjectToOrAvailableForOperatingLeaseAxis=us-gaap_BuildingAndBuildingImprovementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertySubjectToOrAvailableForOperatingLeaseAxis=nen_OtherCategoryOfAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_BoylstonDowntownLPResidentialApartmentsBostonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_BrooksideAssociatesLLCResidentialApartmentsWoburnMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_ClovellyApartmentsLPResidentialApartmentsNashuaNewHampshireMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_Commonwealth1137LPResidentialApartmentsBostonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_Commonwealth1144LPResidentialApartmentsBostonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_ExecutiveApartmentsLPResidentialApartmentsFraminghamMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_HamiltonBattleGreenLLCResidentialApartmentsLexingtonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_HamiltonCypressLLCCommercial1031ExchangeBrooklineMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_HamiltonGreenApartmentsResidentialApartmentsAndoverMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_HamiltonLinewtLLCCommercial1031ExchangeNewtonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_HamiltonOaksAssociatesLLCResidentialApartmentsBrocktonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_HighlandStreetApartmentLPResidentialApartmentsLowellMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_LinhartLPResidentialCommercialNewtonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_NERADeanStAssociatesLLCResidentialApartmentsNorwoodMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_NorthBeacon140LPResidentialUnitsBostonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_OldeEnglishApartmentsLPResidentialApartmentsLowellMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_RedwoodHillsLPResidentialUnitsWorcesterMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_CaptainParkersLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_RiverDriveLPResidentialApartmentsDanversMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_CondominiumUnitsRiversideResidentialUnitsMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_SchoolStAssocLLCResidentialApartmentsFraminghamMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_StaplesPlazaStripMallFraminghamMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_WCBAssociatesLLCResidentialApartmentsBrocktonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_CourtyardAtWestgateResidentialUnitsBurlingtonMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nen_WestgateApartmentsLLCResidentialApartmentsWoburnMassachusettsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |