SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 1) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Cash and cash equivalents	$ 17,662,000us-gaap_CashEquivalentsAtCarryingValue	$ 18,938,000us-gaap_CashEquivalentsAtCarryingValue
Corporate bond	1,079,000nssi_CorporateBond	530,000nssi_CorporateBond
Total	18,741,000nssi_TotalFinancialAssets	19,468,000nssi_TotalFinancialAssets
Level 1 [Member]
Cash and cash equivalents	17,662,000	18,938,000
Corporate bond	1,079,000	530,000
Total	18,741,000	19,468,000
Level 2 [Member]
Cash and cash equivalents
Corporate bond
Total
Level 3 [Member]
Cash and cash equivalents
Corporate bond
Total