The percentage points added to the reference rate to compute fixed rate elections on the debt instrument.

No definition available.

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Namespace Prefix:	naii_
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Balance Type:	na
Period Type:	instant

- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a fluctuating rate when amount is less than threshold.

+ References

No definition available.

+ Details

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

- Definition

The minimum payment amount that may be prepaid on a line of credit facility with a fixed interest rate.

+ References

No definition available.

+ Details

Name:	naii_MinimumPrepaymentAmountUnderLineOfCredit
Namespace Prefix:	naii_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Total current assets divided by total current liabilities.

+ References

No definition available.

+ Details

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Namespace Prefix:	naii_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromLongTermLinesOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

Name:	us-gaap_RatioOfIndebtednessToNetCapital1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Name:	us-gaap_RepaymentsOfLinesOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=naii_CreditAgreementMember
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Data Type:	na
Balance Type:
Period Type:

- Details

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Data Type:	na
Balance Type:
Period Type:

- Details

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Note F - Debt (Details Textual) - USD ($)			12 Months Ended
Note F - Debt (Details Textual) - USD ($)	Feb. 02, 2021	Jul. 01, 2019	Jun. 30, 2020	Dec. 31, 2020
Proceeds from Long-term Lines of Credit			$ 10,000,000
Line of Credit Facility, Remaining Borrowing Capacity				$ 0
Wells Fargo Bank, N.A. [Member] \| Credit Agreement [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 10,000,000
Long-term Debt, Percentage Bearing Fluctuating Interest, Threshold Amount		100,000
Minimum Prepayment Amount Under Line of Credit		$ 100,000
Wells Fargo Bank, N.A. [Member] \| Credit Agreement [Member] \| Subsequent Event [Member]
Line of Credit Facility, Remaining Borrowing Capacity	$ 10,000,000
Repayments of Lines of Credit	10,000,000
Long-term Line of Credit, Total	$ 0
Wells Fargo Bank, N.A. [Member] \| Credit Agreement [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate		1.25%
Debt Instrument Basis Spread on Elected Fixed Rate Borrowing		1.25%
Wells Fargo Bank, N.A. [Member] \| Credit Agreement [Member] \| Maximum [Member]
Ratio of Indebtedness to Net Capital		1.25
Ratio of Total Current Assets to Total Current Liabilities		1.75