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Note G - Economic Dependency - Substantial Net Purchase from Certain Supplier (Details) - Supplier Concentration Risk [Member] - Raw Material Purchases [Member] - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2015 | Dec. 31, 2014
Supplier 1 [Member] |  |  |  |  |  |  |  |
Raw Materials Purchases by Supplier |  | [1] |  | [1] | $ 3,097 |  |  | [1]
% of Total Raw Material Purchases |  | [1] |  | [1] | 12.00% |  |  | [1]
Supplier 2 [Member] |  |  |  |  |  |  |  |
Raw Materials Purchases by Supplier | $ 1,395 |  |  | [1] |  | [1] |  | [1]
% of Total Raw Material Purchases | 12.00% |  |  | [1] |  | [1] |  | [1]
Supplier 3 [Member] |  |  |  |  |  |  |  |
Raw Materials Purchases by Supplier |  | [1] | $ 792 |  |  | [1] | $ 1,827 |
% of Total Raw Material Purchases |  | [1] | 12.00% |  |  | [1] | 12.00% |
Supplier 4 [Member] |  |  |  |  |  |  |  |
Raw Materials Purchases by Supplier |  | [1] | $ 766 |  |  | [1] |  | [1]
% of Total Raw Material Purchases |  | [1] | 11.00% |  |  | [1] |  | [1]
Raw Materials Purchases by Supplier | $ 1,395 |  | $ 1,558 |  | $ 3,097 |  | $ 1,827 |
% of Total Raw Material Purchases | 12.00% |  | 23.00% |  | 12.00% |  | 12.00% |
[1] | Purchases were less than 10% of the respective period's total raw material purchases.

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- Definition Percentage of raw materials purchased from supplier + References No definition available. + Details
Name: | naii_PercentageOfRawMaterialsPurchasedFromSupplier
Namespace Prefix: | naii_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- 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

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis=naii_Supplier3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |