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- Details

Name:	us-gaap_LongtermDebtTypeAxis=fenc_BridgeBankTermLoanMember
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Term Loans (Details) - USD ($) $ / shares in Units, $ in Thousands						3 Months Ended	12 Months Ended	15 Months Ended
	Dec. 18, 2024	Dec. 04, 2023	Sep. 23, 2022	Aug. 19, 2022	Aug. 01, 2022	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2025	Aug. 24, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Debt discount						$ 126	$ 139	$ 126
Petrichor Financing
Debt Instrument [Line Items]
Repayment of debt							13,000
Debt issuance costs			$ 175
Fair value warrants			441
Debt discount			$ 314
Petrichor Financing \| Securities Purchase Agreements \| Secured Convertible Debt
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 45,000
Commitment fee percentage			2.00%
Commitment fees payable in warrants			50.00%
Commitment fees payable in cash or warrants			50.00%
Exercise price of warrants issued			$ 8.11
Exercise term of warrants			5 years
Cash interest accrual rate over Prime					4.50%
Effective interest rate during period								12.00%
Annual payment-in-kind (PIK) interest rate									3.50%
Accrued PIK interest						1,271
Petrichor Financing \| Securities Purchase Agreements \| Secured Convertible Debt \| Maximum
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 45,000
Petrichor Financing \| Securities Purchase Agreements \| First Closing Note
Debt Instrument [Line Items]
Borrowings, face amount				$ 5,000	$ 5,000
Initial conversion price				$ 8.11	$ 8.11
Premium over 5-day VWAP				20.00%	20.00%
VWAP term				5 days	5 days
Petrichor Financing \| Securities Purchase Agreements \| Second Closing Note
Debt Instrument [Line Items]
Borrowings, face amount			$ 20,000
Initial conversion price			$ 7.89
Premium over 5-day VWAP			20.00%
VWAP term			5 days
Petrichor Financing \| Securities Purchase Agreements \| Third Closing Note
Debt Instrument [Line Items]
Borrowings, face amount		$ 5,000
Initial conversion price		$ 7.89
Premium over 5-day VWAP		20.00%
VWAP term		5 days
Petrichor Financing \| Securities Purchase Agreements \| First Closing Warrant
Debt Instrument [Line Items]
Common shares available through issuance of warrants			55,498
Petrichor Financing \| Securities Purchase Agreements \| Second Closing Warrant
Debt Instrument [Line Items]
Common shares available through issuance of warrants			55,498
Petrichor Financing \| SPA First Amendment \| Subsequent Closing Notes
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 15,000								$ 15,000
Remaining borrowing capacity							$ 15,000
Petrichor Financing \| Redemption Agreement \| Note Redemptions
Debt Instrument [Line Items]
Notes payable						$ 19,477		$ 19,477
Repayment of debt	$ 13,000
Principal repayments on debt	11,800
PIK interest repayments on debt	$ 1,271
Bridge Bank \| Bridge Bank Term Loan
Debt Instrument [Line Items]
Repayment of debt				$ 5,000	$ 5,000