Share Capital - Narrative (Details)	May 22, 2018 shares	Dec. 31, 2018 shares
Disclosure of Share Capital, Reserves And Other Equity Interest [Abstract]
Stock conversion ratio	0.10526
Warrants exercisable into common shares	9.5	1,730,894
Number of common shares issuable per warrant	1

Class of Warrant or Right, Number of Securities Called by Each Warrant or Right1

No definition available.

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Namespace Prefix:	oncyf_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant