Note J - Treasury Stock (Details Textual) - USD ($) $ in Millions	Mar. 12, 2021	Sep. 19, 2020	Sep. 18, 2020
Stock Repurchase Program, Authorized Amount	$ 15	$ 12	$ 2
Stock Repurchase Program, Additional Authorized Amount	$ 3

Additional amount of stock repurchase plan authorized.

No definition available.

Name:	naii_StockRepurchaseProgramAdditionalAuthorizedAmount
Namespace Prefix:	naii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration