Represents the number of depository receipts repurchased under the equity repurchase program.

No definition available.

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- Definition

Represents the average price at which depository receipts are repurchased under the equity repurchase program.

+ References

No definition available.

+ Details

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- Definition

Represents the number of depository receipts authorized to be repurchased under the equity repurchase program.

+ References

No definition available.

+ Details

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- Definition

Represents the fixed distribution percentages of the holders of units based on which the entity is required to purchase the proportionate number of specific units with every purchase of depository receipts.

+ References

No definition available.

+ Details

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- Definition

Represents the period over which the entity is permitted to purchase its depository receipts.

+ References

No definition available.

+ Details

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- Definition

Represents the number of treasury units outstanding as on the balance sheet date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:sharesItemType
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Period Type:	instant

- Definition

Represents the average price at which units are repurchased under the equity repurchase program.

+ References

No definition available.

+ Details

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Namespace Prefix:	nen_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of units that were previously issued and have been repurchased during the year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6828210&loc=d3e70191-108054

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Units that were previously issued and have been repurchased during the year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB TOPIC 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

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TREASURY UNITS (Details)		12 Months Ended			113 Months Ended
TREASURY UNITS (Details)	Mar. 10, 2015 shares	Dec. 31, 2017 USD ($) $ / item shares	Dec. 31, 2016 USD ($) $ / item shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2016 USD ($) $ / item shares	Aug. 20, 2007 shares
Treasury units		55,839
Period for repurchase of depository receipts	5 years
Depository receipts authorized to be repurchased	2,000,000					300,000
Number of depository receipts repurchased					1,365,306
Repurchase price of depository receipts (in dollars per receipt) \| $ / item					27.14
Units repurchased (in shares)		23	965	2,279
Total cost of repurchase \| $		$ 42,548	$ 1,634,945	$ 3,429,953	$ 40,274,000
General Partnership
Treasury units		559
Fixed distribution percentage of unit holders		1.00%
Number of depository receipts repurchased					162
Total cost of repurchase \| $		$ 426	$ 16,181	$ 33,878
Treasury Units
Units repurchased (in shares)		23	965	2,279
Class A
Fixed distribution percentage of unit holders		80.00%
Repurchase price of units (in dollars per unit) \| $ / item					814.20
Total cost of repurchase \| $		$ 34,038	$ 1,311,328	$ 2,752,393
Class B
Fixed distribution percentage of unit holders		19.00%
Number of depository receipts repurchased					3,072
Total cost of repurchase \| $		$ 8,084	$ 307,436	$ 643,682
Class A
Treasury units		44,671
Repurchase price of depository receipts (in dollars per receipt) \| $ / item		62.00	55.89
Repurchase price of units (in dollars per unit) \| $ / item		1,860.00	1,676.70
Class A \| Limited Partner
Total cost of repurchase \| $		$ 34,038	$ 1,311,328
Class B
Treasury units		10,609
Fixed distribution percentage of unit holders		19.00%
Class B \| Limited Partner
Total cost of repurchase \| $		$ 8,084
Class B \| General Partnership
Repurchase price of units (in dollars per unit) \| $ / item					926.26
Treasury Units \| General Partnership
Units repurchased (in shares)		0.2	10
Treasury Units \| Class A \| Limited Partner
Number of depository receipts repurchased			23,159
Treasury Units \| Class B \| Limited Partner
Units repurchased (in shares)		4.3	183