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

No definition available.

Name:	naii_DebtInstrumentBasisSpreadOnElectedFixedRateBorrowing
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

Name:	naii_DebtPrePaymentPenalty
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

The number of consecutive days that the outstanding balance must be zero on a line of credit as part of the agreement.

+ References

No definition available.

+ Details

Name:	naii_LineOfCreditCovenantNumberOfConsecutiveDaysThatOutstandingBalanceMustBeZero
Namespace Prefix:	naii_
Data Type:	xbrli:durationItemType
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

Name:	naii_LineOfCreditFacilityMaximumAmountOutstandingAfterReduction
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

Name:	naii_LineOfCreditFacilityMaximumBorrowingCapacityAnnualReduction
Namespace Prefix:	naii_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount that a balance for a line of credit must be maintained at for a predetermined amount of days as part of the agreement.

+ References

No definition available.

+ Details

Name:	naii_LineOfCreditFacilityOutstandingDailyBalanceDuringPeriod
Namespace Prefix:	naii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

Amount of net income after taxes that must be maintained by the borrower in a line of credit facility.

+ References

No definition available.

+ Details

Name:	naii_NetIncomeRequiredInFutureForIncomeCovenant
Namespace Prefix:	naii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: 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

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
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

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
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)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-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=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
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

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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 rate subject to change from time to time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtPercentageBearingVariableInterestAmount
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

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

Note E - Debt (Details Textual)	9 Months Ended			9 Months Ended
Note E - Debt (Details Textual)	Mar. 31, 2015 USD ($)	Feb. 19, 2007 USD ($)	Mar. 31, 2015 Maximum [Member]	Mar. 31, 2015 Minimum [Member]	Mar. 31, 2015 London Interbank Offered Rate (LIBOR) [Member]	Mar. 31, 2015 Natural Alternatives International Europe SA [Member] Fixed Loans [Member] USD ($)	Mar. 31, 2015 Natural Alternatives International Europe SA [Member] Fixed Loans [Member] CHF	Mar. 31, 2015 Natural Alternatives International Europe SA [Member]	Feb. 19, 2007 Natural Alternatives International Europe SA [Member] CHF	Sep. 22, 2006 Natural Alternatives International Europe SA [Member] USD ($)	Sep. 22, 2006 Natural Alternatives International Europe SA [Member] CHF
Line of Credit Facility, Maximum Borrowing Capacity	$ 5,000,000									$ 1,300,000	1,300,000
Line of Credit Facility, Commitment Fee Amount	10,000
Net Income Required in Future for Income Covenant	750,000
Long-term Line of Credit	0us-gaap_LineOfCredit
Ratio of Indebtedness to Net Capital			1.25
Long-term Debt, Percentage Bearing Variable Interest, Amount	100,000
Debt Instrument, Basis Spread on Variable Rate					1.75%
Debt Instrument Basis Spread on Elected Fixed Rate Borrowing					1.75%
Line of Credit Facility Outstanding Daily Balance During Period	0
Line of Credit Covenant Number of Consecutive Days That Outstanding Balance Must Be Zero				30 days
Minimum Prepayment Amount Under Line of Credit	100,000
Line of Credit Facility Maximum Borrowing Capacity Annual Reduction										166,000	160,000
Line of Credit Facility Maximum Amount Outstanding after Reduction		518,000							500,000
Debt Instrument, Term								2 years
Debt Instrument, Interest Rate, Stated Percentage								5.00%
Debt Prepayment Penalty Rate						0.10%	0.10%
Debt Pre Payment Penalty						1,037	1,000
Line of Credit Facility, Current Borrowing Capacity	$ 5,500,000