v3.25.3

Related Party Transactions (Details) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
Related Party Transactions (Details) - USD ($)	Jun. 17, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Dec. 18, 2023
Related Party Transactions [Line Items]
Accounts payable
Subscription Agreement [Member] \| Non-convertible Debenture [Member]
Related Party Transactions [Line Items]
Principal amount						$ 5,000,000
Dr. Meier [Member]
Related Party Transactions [Line Items]
Percentage of success fees received	10.00%
Related expenses			$ 19,000		$ 54,000
PMX Investor [Member]
Related Party Transactions [Line Items]
Subscription agreement stockholder percentage							5.00%

Subscription agreement stocholder percentage.

+ References

No definition available.

+ Details

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Namespace Prefix:	onco_
Data Type:	dtr:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Success fees.

+ References

No definition available.

+ Details

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Namespace Prefix:	onco_
Data Type:	dtr:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of obligations incurred and payable classified as other.

+ References

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-Section S99
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-Subparagraph (SX 210.9-03(15)(5))
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+ Details

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

- Definition

Costs of sales and operating expenses for the period incurred from transactions with related parties.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Subparagraph (SX 210.5-03(2))
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Balance Type:	debit
Period Type:	duration

- Definition

Amount of principal of debt issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(1))
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+ Details

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

- 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/disclosureRef
-Topic 850
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+ Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=onco_NonConvertibleDebentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=onco_DrMeierMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=onco_PMXInvestorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Onconetix, Inc. 10-Q