Document And Entity Information - USD ($)	12 Months Ended
	Jun. 30, 2020	Sep. 14, 2020	Dec. 31, 2019
Document And Entity Information
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	NAPCO SECURITY TECHNOLOGIES, INC
Entity Central Index Key	0000069633
Current Fiscal Year End Date	--06-30
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 339,054,796
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	NSSC
Entity Common Stock, Shares Outstanding		18,347,351