ADVANCE RENTAL PAYMENTS AND SECURITY DEPOSITS (Details) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
ADVANCE RENTAL PAYMENTS AND SECURITY DEPOSITS
Period for advance rental payment	1 month
Amount received for prepaid rent	$ 2,127,000	$ 1,954,000
Security deposits	$ 2,420,000	$ 2,381,000

Represents amounts received from tenants for prepaid rents which are included in cash and cash equivalents.

No definition available.

Name:	nen_PrepaidRentReceivedIncludedInCashAndCashEquivalents
Namespace Prefix:	nen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant