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v3.20.4

Note G - Economic Dependency - Substantial Net Purchase From Certain Suppliers (Details) - Supplier Concentration Risk [Member] - Raw Material Purchases [Member] - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2020 | Dec. 31, 2019
Raw Material Purchases by Supplier | $ 6,412 | $ 1,734 | $ 9,787 | $ 3,227
Supplier 1 [Member] |  |  |  |
Raw Material Purchases by Supplier | $ 6,412 | $ 1,734 | $ 9,787 | $ 3,227

X
- Definition Raw material purchases by supplier + References No definition available. + Details
Name: | naii_RawMaterialPurchasesBySupplier
Namespace Prefix: | naii_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_ConcentrationRiskByTypeAxis=us-gaap_SupplierConcentrationRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=naii_RawMaterialPurchasesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis=naii_Supplier1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |