Represents the useful life of constituents of rental properties.

No definition available.

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of units in a real estate property owned as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The cumulative amount of depreciation for real estate property held for investment purposes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(3))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

RENTAL PROPERTIES (Details)	12 Months Ended
RENTAL PROPERTIES (Details)	Dec. 31, 2017 USD ($) property item	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 item
RENTAL PROPERTIES
Number of units \| item			1,033
Rental properties
Total fixed assets	$ 311,951,597	$ 263,659,293
Less: Accumulated depreciation	(104,797,803)	(94,196,482)
Total fixed assets, net	207,153,794	169,462,811
Land, improvements and parking lots
Rental properties
Total fixed assets	$ 65,087,214	52,612,929
Land, improvements and parking lots \| Minimum
Rental properties
Useful Life	15 years
Land, improvements and parking lots \| Maximum
Rental properties
Useful Life	40 years
Buildings and improvements
Rental properties
Total fixed assets	$ 201,844,565	173,536,288
Buildings and improvements \| Minimum
Rental properties
Useful Life	15 years
Buildings and improvements \| Maximum
Rental properties
Useful Life	40 years
Kitchen cabinets
Rental properties
Total fixed assets	$ 12,338,627	8,738,323
Kitchen cabinets \| Minimum
Rental properties
Useful Life	5 years
Kitchen cabinets \| Maximum
Rental properties
Useful Life	10 years
Carpets
Rental properties
Total fixed assets	$ 8,802,831	7,621,292
Carpets \| Minimum
Rental properties
Useful Life	5 years
Carpets \| Maximum
Rental properties
Useful Life	10 years
Air conditioning
Rental properties
Total fixed assets	$ 641,079	690,535
Air conditioning \| Minimum
Rental properties
Useful Life	5 years
Air conditioning \| Maximum
Rental properties
Useful Life	10 years
Laundry equipment
Rental properties
Total fixed assets	$ 263,275	269,784
Laundry equipment \| Minimum
Rental properties
Useful Life	5 years
Laundry equipment \| Maximum
Rental properties
Useful Life	7 years
Elevators
Rental properties
Total fixed assets	$ 1,139,296	1,139,296
Elevators \| Minimum
Rental properties
Useful Life	20 years
Elevators \| Maximum
Rental properties
Useful Life	40 years
Swimming pools
Rental properties
Total fixed assets	$ 444,629	444,629
Swimming pools \| Minimum
Rental properties
Useful Life	10 years
Swimming pools \| Maximum
Rental properties
Useful Life	30 years
Equipment
Rental properties
Total fixed assets	$ 11,163,864	10,029,639
Equipment \| Minimum
Rental properties
Useful Life	5 years
Equipment \| Maximum
Rental properties
Useful Life	30 years
Motor vehicles
Rental properties
Total fixed assets	$ 216,260	237,954
Useful Life	5 years
Fences
Rental properties
Total fixed assets	$ 37,465	37,465
Fences \| Minimum
Rental properties
Useful Life	5 years
Fences \| Maximum
Rental properties
Useful Life	15 years
Furniture and fixtures
Rental properties
Total fixed assets	$ 9,390,021	8,127,100
Furniture and fixtures \| Minimum
Rental properties
Useful Life	5 years
Furniture and fixtures \| Maximum
Rental properties
Useful Life	7 years
Smoke alarms
Rental properties
Total fixed assets	$ 582,471	$ 174,059
Smoke alarms \| Minimum
Rental properties
Useful Life	5 years
Smoke alarms \| Maximum
Rental properties
Useful Life	7 years
Wholly owned properties
RENTAL PROPERTIES
Number of properties \| property	26
Investment Properties
RENTAL PROPERTIES
Number of units \| item	1,033	1,033
Investment Properties \| Minimum
RENTAL PROPERTIES
Ownership interest (as a percent)	40.00%
Investment Properties \| Maximum
RENTAL PROPERTIES
Ownership interest (as a percent)	50.00%
Residential and mixed-use properties \| Wholly owned properties
RENTAL PROPERTIES
Number of units \| item	2,632
Number of properties \| property	22
Residential and mixed-use properties \| Partially owned properties
RENTAL PROPERTIES
Number of units \| item	722
Number of properties \| item	9
Residential and mixed-use properties \| Partially owned properties \| Minimum
RENTAL PROPERTIES
Ownership interest (as a percent)	40.00%
Residential and mixed-use properties \| Investment Properties \| Partially owned properties
RENTAL PROPERTIES
Number of properties \| item	9
Residential and mixed-use properties \| Investment Properties \| Partially owned properties \| Minimum
RENTAL PROPERTIES
Ownership interest (as a percent)	40.00%
Residential and mixed-use properties \| Investment Properties \| Partially owned properties \| Maximum
RENTAL PROPERTIES
Ownership interest (as a percent)	50.00%
Condominium \| Wholly owned properties
RENTAL PROPERTIES
Number of units \| item	19
Number of properties \| property	1