Represents the useful life of constituents of rental properties.

No definition available.

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Namespace Prefix:	nen_
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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 Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Reference 2: 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=6382943&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

+ Details

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Data Type:	num:percentItemType
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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 7

+ 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

+ Details

Name:	us-gaap_RealEstateInvestmentPropertyAtCost
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

+ Details

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

- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RealEstatePropertiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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RENTAL PROPERTIES (Details) (USD $)	9 Months Ended
RENTAL PROPERTIES (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Rental properties
Total fixed assets	$ 223,103,303	$ 158,624,893
Less: Accumulated depreciation	(68,838,718)	(63,651,293)
Total fixed assets, net	154,264,585	94,973,600
Land, improvements and parking lots
Rental properties
Total fixed assets	43,853,519	27,743,726
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	152,671,201	118,739,283
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	6,261,506	3,544,868
Kitchen cabinets \| Minimum
Rental properties
Useful Life	5 years
Kitchen cabinets \| Maximum
Rental properties
Useful Life	10 years
Carpets
Rental properties
Total fixed assets	6,225,566	3,218,975
Carpets \| Minimum
Rental properties
Useful Life	5 years
Carpets \| Maximum
Rental properties
Useful Life	10 years
Air conditioning
Rental properties
Total fixed assets	779,446	746,043
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	435,218	378,806
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	235,242
Swimming pools \| Minimum
Rental properties
Useful Life	10 years
Swimming pools \| Maximum
Rental properties
Useful Life	30 years
Equipment
Rental properties
Total fixed assets	5,234,614	1,529,904
Equipment \| Minimum
Rental properties
Useful Life	5 years
Equipment \| Maximum
Rental properties
Useful Life	7 years
Motor vehicles
Rental properties
Total fixed assets	101,657	101,657
Useful Life	5 years
Fences
Rental properties
Total fixed assets	32,695	22,445
Fences \| Minimum
Rental properties
Useful Life	5 years
Fences \| Maximum
Rental properties
Useful Life	15 years
Furniture and fixtures
Rental properties
Total fixed assets	5,703,942	1,031,348
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	$ 220,014	$ 193,298
Smoke alarms \| Minimum
Rental properties
Useful Life	5 years
Smoke alarms \| Maximum
Rental properties
Useful Life	7 years
Residential and mixed-use properties
RENTAL PROPERTIES
Number of units	2,412
Number of properties	19
Residential and mixed-use properties \| Partially owned properties
RENTAL PROPERTIES
Number of units	798
Number of properties	9
Residential and mixed-use properties \| Partially owned properties \| Minimum
RENTAL PROPERTIES
Percentage of ownership interest	40.00%
Residential and mixed-use properties \| Partially owned properties \| Maximum
RENTAL PROPERTIES
Percentage of ownership interest	50.00%
Condominium
RENTAL PROPERTIES
Number of units	19