Name:	onct_ContingentValueRightEntitledPerEachShareOfCommonStockHeld
Namespace Prefix:	onct_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Percentage of net proceeds available to the stockholders eligible for contingent value rights during the 15-year period after closing from the grant, sale or transfer of rights to the Company's SARD and SARM technology.

No definition available.

Name:	onct_PercentageOfNetProceedsEntitledToReceiveDuringPeriodSpecifiedAfterClosingFromGrantSaleOrTransferOfRights
Namespace Prefix:	onct_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Period from closing during which the grant, sale or transfer of rights to the Company's SARD or SARM technology could trigger a payment under the CVR Agreement.

No definition available.

Name:	onct_PeriodWhichGrantSaleOrTransferOfRightsToCompanySardOrSarmTechnologyCouldTriggerPaymentUnderCvrAgreement
Namespace Prefix:	onct_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Period from closing during which percentage of net proceeds payment would be payable under the CVR.

No definition available.

Name:	onct_PeriodWhichPaymentOfPercentageOfNetProceedsWouldBePayableUnderCVR
Namespace Prefix:	onct_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.