Commitments and Contingencies (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Rostislav Raykov [Member]
Severance Costs Payable In Case Of Termination Other Than For Cause	$ 400,000
Robert Andrade [Member]
Severance Costs Payable In Case Of Termination Other Than For Cause	$ 145,000

Amount of expenses payable for special or contractual termination benefits provided to current employees in the event of termination other than for cause.

No definition available.

Name:	fenc_SeveranceCostsPayableInCaseOfTerminationOtherThanForCause
Namespace Prefix:	fenc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant