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_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of penalties associated with the prepayment of debt.

+ References

No definition available.

+ Details

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

- Definition

Percentage of penalties associated with the prepayment of debt.

+ References

No definition available.

+ Details

Name:	naii_DebtPrepaymentPenaltyRate
Namespace Prefix:	naii_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum amount outstanding after an annual reduction on a line of credit facility.

+ References

No definition available.

+ Details

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

- Definition

Amount of annual reduction on a line of credit facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	naii_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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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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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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

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
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-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

+ Details

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

- Definition

Amount of the fee for available but unused credit capacity under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-Topic 944
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20, 22
-Article 5

+ Details

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

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

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

- Details

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- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=naii_CreditAgreementMember
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- Details

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- Details

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Note E - Debt (Details Textual)		6 Months Ended
Note E - Debt (Details Textual)	Feb. 01, 2016 USD ($)	Dec. 31, 2015 CHF (SFr)	Dec. 31, 2015 USD ($)	Jan. 31, 2016 USD ($)	Feb. 19, 2007 CHF (SFr)	Feb. 19, 2007 USD ($)	Sep. 22, 2006 CHF (SFr)	Sep. 22, 2006 USD ($)
Subsequent Event [Member] \| 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
Subsequent Event [Member] \| 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%
Subsequent Event [Member] \| Wells Fargo Bank, N.A. [Member] \| Credit Agreement [Member]
Long-term Line of Credit	$ 0
Line of Credit Facility, Commitment Fee Amount	0
Line of Credit Facility, Maximum Borrowing Capacity	10,000,000			$ 5,000,000
Long-term Debt, Percentage Bearing Fluctuating Interest, Threshold Amount	100,000
Minimum Prepayment Amount Under Line of Credit	$ 100,000
Fixed Loans [Member] \| Natural Alternatives International Europe SA [Member] \| Line of Credit [Member]
Debt Prepayment Penalty Rate		0.10%	0.10%
Debt Pre Payment Penalty		SFr 1,000	$ 1,009
Natural Alternatives International Europe SA [Member] \| Maximum [Member] \| Line of Credit [Member]
Debt Instrument, Term		2 years	2 years
Natural Alternatives International Europe SA [Member] \| Line of Credit [Member]
Debt Instrument, Interest Rate, Stated Percentage			5.00%
Natural Alternatives International Europe SA [Member]
Long-term Line of Credit			$ 0
Line of Credit Facility, Maximum Borrowing Capacity							SFr 1,300,000	$ 1,300,000
Line of Credit Facility Maximum Borrowing Capacity Annual Reduction							SFr 160,000	$ 161,000
Line of Credit Facility Maximum Amount Outstanding after Reduction					SFr 500,000	$ 505,000
Long-term Debt			0
Line of Credit Facility, Remaining Borrowing Capacity			$ 5,500,000