Name:	frevsob_Covid19PandemicDetailsLineItems
Namespace Prefix:	frevsob_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Rent abatements during the period.

No definition available.

Name:	frevsob_RentAbatements
Namespace Prefix:	frevsob_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Rental revenue deemed uncollectible.

No definition available.

Name:	frevsob_RentalRevenueDeemedUncollectible
Namespace Prefix:	frevsob_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount of total deferred payments.

No definition available.

Name:	frevsob_TotalDeferredPayments
Namespace Prefix:	frevsob_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount of unamortized leasing commissions.

No definition available.

Name:	frevsob_UnamortizedLeasingCommissions
Namespace Prefix:	frevsob_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of uncollected rents.

No definition available.

Name:	frevsob_UncollectedRents
Namespace Prefix:	frevsob_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=126905981&loc=d3e2420-110228

Name:	us-gaap_AssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations.

No definition available.

Name:	us-gaap_OtherOperatingIncomeExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3291-108585

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The net book value of the asset(s) sold in connection with the sale of the property to another party and lease back to the seller.

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 55
-Paragraph 51
-URI https://asc.fasb.org/extlink&oid=123386837&loc=d3e51840-112757

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 40
-Section 50
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=128295416&loc=SL77919786-209982

Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 55
-Paragraph 52
-URI https://asc.fasb.org/extlink&oid=123386837&loc=d3e51843-112757

Reference 4: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 55
-Paragraph 50
-URI https://asc.fasb.org/extlink&oid=123386837&loc=d3e51831-112757

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

The amount of an asset, typically cash, provided to a counterparty to provide certain assurance of performance by the entity pursuant to the terms of a written or oral agreement, such as a lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(17))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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

Difference between actual rental income due and rental income recognized on a straight-line basis.