RENTAL INCOME (Rent Receivable) (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
RENTAL INCOME.
Allowance for doubtful rent receivable	$ 630	$ 879
Recognizing rental income from non-cancelable commercial leases with future rental increases on a straight-line basis	$ 31

Represents the amount resulting from recognizing rental income from non-cancelable commercial leases with future rental increases on a straight-line basis, which is included in rents receivable.

No definition available.

Name:	nen_OperatingLeasesRentalIncomeWithFutureRentalIncreases
Namespace Prefix:	nen_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant