Name:	nssc_CommitmentAnnualSalary
Namespace Prefix:	nssc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The rate applied to the most recent 5-year average of annual salaries, as defined, to calculate termination pay the entity has committed to pay under specified circumstances.

No definition available.

Name:	nssc_CommitmentTerminationPay
Namespace Prefix:	nssc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Number of employment agreement.

No definition available.

Name:	nssc_NumberOfEmploymentAgreement
Namespace Prefix:	nssc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Minimum number of months either party gives the other notice of non-renewal at prior to the end of the applicable term.

No definition available.

Name:	nssc_NumberOfMonthsNoticeForNonRenewalEmploymentAgreement
Namespace Prefix:	nssc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The number of months of health insurance that employers owe employees when their employment ends through a layoff or other termination without cause.

No definition available.

Name:	nssc_NumberOfMonthsSeveranceBenefitOfHealthInsurance
Namespace Prefix:	nssc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The number of months of wages that employers owe employees when their employment ends through a layoff or other termination without cause.

No definition available.

Name:	nssc_NumberOfMonthsSeveranceBenefitOfSalary
Namespace Prefix:	nssc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Number of severance agreement.

No definition available.

Name:	nssc_NumberOfSeveranceAgreement
Namespace Prefix:	nssc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-4

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
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-Section 50
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-URI https://asc.fasb.org//1943274/2147483076/450-20-50-4

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
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-URI https://asc.fasb.org//1943274/2147483076/450-20-50-9

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
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-Section 50
-Paragraph 9
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-9