401(k) Plan (Narrative) (Detail) (Napco Technologies 401 k Plan [Member], USD $)	3 Months Ended		6 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Napco Technologies 401 k Plan [Member]
Schedule of Deferred Compensation Plans [Line Items]
Deferred compensation plan expense	$ 41,000	$ 25,000	$ 67,000	$ 51,000