Name:	nssc_CommitmentAnnualSalary
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Data Type:	xbrli:monetaryItemType
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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:	num:percentItemType
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Period Type:	duration

The year in which an agreement expires.

No definition available.

Name:	nssc_ExpirationYear
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Balance Type:	na
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The number of contracts, agreements or arrangements in the disclosure as of a point in time.

No definition available.

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Data Type:	xbrli:decimalItemType
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Period Type:	duration

As of the reporting date, the annual amount of minimum rent the entity is obligated to pay under the terms of an operating lease.

No definition available.

Name:	nssc_OperatingLeaseCommitmentAnnualRent
Namespace Prefix:	nssc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Area of land held.

No definition available.

Name:	us-gaap_AreaOfLand
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
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Period Type:	instant

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

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Namespace Prefix:
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