Name:	naii_DefinedBenefitPlanExpectedFutureBenefitPayment
Namespace Prefix:	naii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of benefits for defined benefit plan expected to be paid in fifth fiscal year following latest fiscal year.

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Amount of benefits for defined benefit plan expected to be paid in fourth fiscal year following latest fiscal year.

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of benefits for defined benefit plan expected to be paid in third fiscal year following latest fiscal year.

Name:	us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.