Represents the percentage of sales returns, rebates and allowances.

No definition available.

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Namespace Prefix:	nssc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the term of limited standard warranty for defective products.

+ References

No definition available.

+ Details

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Namespace Prefix:	nssc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of liability for consideration received or receivable from customer which is not included in transaction price, when consideration is expected to be refunded to customer, classified as current.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 55
-Paragraph 27
-URI http://asc.fasb.org/extlink&oid=121551570&loc=SL49130611-203046-203046

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of right to recover product from customer on settling refund liability, classified as current.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Description of payment terms in contract with customer. Includes, but is not limited to, timing of payment, existence of financing component, variability of consideration and constraint on variable consideration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Revenue Recognition and Contracts with Customers (Details) - USD ($)	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Jun. 30, 2020
Refund liabilities	$ 3,791,000		$ 3,791,000		$ 3,331,000
Sales returns, rebates and allowances as a percentage of net sales	15.00%	12.00%	16.00%	13.00%
Minimum
Payment terms (in days)			30
Standard warranty term			24 months
Maximum
Payment terms (in days)			180
Standard warranty term			36 months
Other current assets
Return related assets	$ 840,000		$ 840,000		$ 701,000