Note J - Treasury Stock (Details Textual) - USD ($) $ in Millions	Jan. 14, 2022	Mar. 12, 2021	Sep. 19, 2020
Stock Repurchase Program, Additional Authorized Amount		$ 3	$ 2
Stock Repurchase Program, Authorized Amount		$ 15	$ 12
Subsequent Event [Member]
Stock Repurchase Program, Additional Authorized Amount	$ 3
Stock Repurchase Program, Authorized Amount	$ 18

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