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Note G - Economic Dependency (Details) - Total Raw Material Purchases (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 6 Months Ended
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2012
Concentration Risk [Line Items] |  |
Raw Material Purchases by Supplier (in Dollars) | $ 732 | $ 1,223
% of Total Raw Material Purchase | 13.00% | 10.00%
Supplier 1 [Member] |  |
Concentration Risk [Line Items] |  |
Raw Material Purchases by Supplier (in Dollars) | $ 732 | $ 1,223
% of Total Raw Material Purchase | 13.00% | 10.00%

X
- Definition Percentage of Raw Materials Purchased From Supplier + References No definition available. + Details
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Namespace Prefix: | naii_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Raw Material Purchases from Major Suppliers + References No definition available. + Details
Name: | naii_RawMaterialPurchasesBySupplier
Namespace Prefix: | naii_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
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Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration