Leases - Summary of Changes in Lease Receivables (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Balance, beginning of the year	$ 11,045	$ 33,500
Sale of assets in sale leaseback		(22,508)
Interest	791	11,019
Lease payments received	(855)	(10,966)
Balance, end of the period	10,981	11,045
Less current portion	(3,495)	(3,450)
Long term lease receivables	$ 7,486	$ 7,595

Lease receivables Interest during the period.

No definition available.

Name:	ffntf_LeaseReceivablesInterestDuringPeriod
Namespace Prefix:	ffntf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Lease receivables Lease Payment received during the period.

+ References

No definition available.

+ Details

Name:	ffntf_LeaseReceivablesLeasePaymentReceivedDuringPeriod
Namespace Prefix:	ffntf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Lease receivables sale of assets in sale lease back during period.

+ References

No definition available.

+ Details

Name:	ffntf_LeaseReceivablesSaleOfAssetsInSaleLeaseBackDuringPeriod
Namespace Prefix:	ffntf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This item represents the current receivable for an incentive or inducement contractually stipulated between parties to a lease whereby the lessor has committed to provide the entity (lessee) with a cash payment as inducement to enter the lease. The receivable is due within one year. For classified balance sheets, this element represents the current amount receivable, that is amounts expected to be collected within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LeaseIncentiveReceivableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Noncurrent portion of receivables for an incentive or inducement contractually stipulated between parties to a lease whereby the lessor has committed to provide the entity (lessee) with a cash payment as inducement to enter the lease.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LeaseIncentiveReceivableNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term guaranteed by lessee or other third party unrelated to lessor, from sales-type and direct financing leases.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919391-209981

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919379-209981

+ Details

Name:	us-gaap_SalesTypeAndDirectFinancingLeasesLeaseReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant