OTHER INTANGIBLE ASSETS - Schedule of other intangible assets - (Details 1) - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025
Finite-Lived Intangible Assets [Line Items]
2025	$ 962
2026	533
2027	303
2028	295
2029	290
Thereafter	868
Other intangible assets - net	3,251	$ 2,992
Software License [Member]
Finite-Lived Intangible Assets [Line Items]
2025	378
2026	32
2027
2028
2029
Thereafter
Other intangible assets - net	410
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
2025	250
2026	188
2027
2028
2029
Thereafter
Other intangible assets - net	438
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
2025	134
2026	113
2027	103
2028	95
2029	90
Thereafter	404
Other intangible assets - net	939
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
2025	200
2026	200
2027	200
2028	200
2029	200
Thereafter	464
Other intangible assets - net	$ 1,464

Amount of amortization for asset, excluding financial asset and goodwill, lacking physical substance with finite life expected to be recognized after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 40
-SubTopic 30
-Topic 350
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482640/350-30-55-40

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481283/985-20-50-2

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-20

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-20

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 38
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-38

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 12: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 14: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 15: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 16: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 17: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 18: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-31

Reference 19: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 29
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-29

Reference 20: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 29
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-29

Reference 21: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-20

Reference 22: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-20

Reference 23: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 24: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 25: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 26: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 27: http://www.xbrl.org/2003/role/exampleRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479876/805-20-55-14

Reference 28: http://www.xbrl.org/2003/role/exampleRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 40
-SubTopic 30
-Topic 350
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482640/350-30-55-40

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482686/350-30-45-1

Reference 32: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-3

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481283/985-20-50-2

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Topic 926
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483154/926-20-50-5

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482686/350-30-45-1

+ Details

Name:	us-gaap_IntangibleAssetsNetExcludingGoodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=FONR_SoftwareLicenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_NoncompeteAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_PatentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: