Note I - Commitments (Details Textual) $ in Millions	12 Months Ended
Jun. 30, 2017 USD ($) ft²	Jun. 30, 2016 USD ($)
Operating Leases, Rent Expense, Net \| $	$ 3.0	$ 3.1
California [Member]
Operating Lease Facility Area	162,000
SWITZERLAND \| Natural Alternatives International Europe SA [Member]
Operating Lease Facility Area	94,217
Lessee, Operating Lease, Renewal Term	5 years
Lessee, Operating Lease, Term of Contract	5 years

Area of leased facility in square feet.

No definition available.

Name:	naii_OperatingLeaseFacilityArea
Namespace Prefix:	naii_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeLeasingArrangementsOperatingLeasesRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_LesseeLeasingArrangementsOperatingLeasesTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

+ Details

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

- Details

Name:	us-gaap_StatementGeographicalAxis=naii_CaliforniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=country_CH
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=naii_NaturalAlternativesInternationalEuropeSaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: