Additional service expenses.

No definition available.

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

- Definition

Asset management fees percentage rate.

+ References

No definition available.

+ Details

Name:	frevsob_AssetManagementFeesPercentageRate
Namespace Prefix:	frevsob_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate costs related to management of owned properties during the reporting period.

+ References

No definition available.

+ Details

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

- Definition

The expense incurred to persons or entities for securing insurance coverage for properties and subsidiaries.

+ References

No definition available.

+ Details

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

- Definition

Amount of commissions expense incurred because the lessor of real estate obtained a lessee for a rental property through a real estate agent and generally recurring costs associated with operations.

+ References

No definition available.

+ Details

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

- Definition

Loan commission.

+ References

No definition available.

+ Details

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

- Definition

Pro-rata share based funding amount.

+ References

No definition available.

+ Details

Name:	frevsob_ProrataShareBasedFundingAmount
Namespace Prefix:	frevsob_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Repayment to affiliate.

+ References

No definition available.

+ Details

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

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(5))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.15(a))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

+ Details

Name:	us-gaap_AccruedLiabilitiesCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of debt and lease obligation, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(21))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the total principal payments made during the annual reporting period.

+ 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(22))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount of payable due to an entity that is affiliated with the reporting entity by means of direct or indirect ownership. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 3: 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(19)(a)(5))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04(12)(b)(3))
-URI https://asc.fasb.org/extlink&oid=120401414&loc=d3e603758-122996

+ Details

Name:	us-gaap_DueToAffiliateCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(c))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Fees charged annually for the professional services of a trustee, usually quoted as a percentage of the funds being managed. The fee for appointing an offshore Trustee is included in the trust price.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI https://asc.fasb.org/extlink&oid=126953954&loc=SL114868664-224227

+ Details

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

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=frevsob_Rotunda100MembersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_Subsidiaries7Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_Subsidiaries8Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_Subsidiaries9Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_HTPKEMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_Subsidiaries10Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_DamascusPropertyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_WestridgeSquarePropertyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_BouldersPropertyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_PreaknessShoppingCenterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_GrandeRotundaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=frevsob_WestFREITMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_DirectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_ImmediateFamilyMemberOfManagementOrPrincipalOwnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=frevsob_Director2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=frevsob_DavidHekemianMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Management agreement, fees and transactions with related party (Details) - USD ($)	3 Months Ended			9 Months Ended
	Jul. 31, 2022	Jul. 31, 2021	Apr. 30, 2021	Jul. 31, 2022	Jul. 31, 2021	Mar. 10, 2022	Dec. 30, 2021	Oct. 31, 2021
Related Party Transaction [Line Items]
Insurance commissions	$ 40,000	$ 37,000		$ 40,000	$ 47,000
Asset management fees	318,000	538,000		1,129,000	1,625,000
Secured loans receivable								$ 5,292,000
Provident Bank [Member]
Related Party Transaction [Line Items]
Loan commission				32,500
Rotunda 100 members [Member]
Related Party Transaction [Line Items]
Secured loans receivable	$ 5,300,000			$ 5,300,000
Principal amount on notes paid off								4,000,000
Unpaid accrued interest								1,292,000
Grande Rotunda, LLC [Member]
Related Party Transaction [Line Items]
Ownership by noncontrolling owners (percentage)	40.00%			40.00%
Ownership by parent (percentage)	50.00%			50.00%
Due to affiliate							$ 3,300,000	3,300,000
Principal amount on notes paid off							$ 31,000,000	$ 7,000,000
FREIT [Member]
Related Party Transaction [Line Items]
Ownership by noncontrolling owners (percentage)	40.00%			40.00%
Pro-rata share based funding amount						$ 200,000
Promissory note						400,000
Rotunda [Member]
Related Party Transaction [Line Items]
Ownership by noncontrolling owners (percentage)	60.00%			60.00%
Ownership by parent (percentage)	73.00%			73.00%
Loan commission				$ 4,777,000
Pro-rata share based funding amount						300,000
H-TPKE [Member]
Related Party Transaction [Line Items]
Promissory note						600,000
Wayne PSC [Member]
Related Party Transaction [Line Items]
Pro-rata share based funding amount						$ 500,000
Damascus Property [Member]
Related Party Transaction [Line Items]
Loan commission				917,000
Westridge Square Property [Member]
Related Party Transaction [Line Items]
Loan commission				525,000
Boulders Property [Member]
Related Party Transaction [Line Items]
Loan commission				75,000
Preakness Shopping Center [Member]
Related Party Transaction [Line Items]
Loan commission				94,000
Grande Rotunda [Member]
Related Party Transaction [Line Items]
Loan commission					150,000
Repayment to affiliate					2,800,000
WestFREIT [Member]
Related Party Transaction [Line Items]
Loan commission					54,000
Managing Agent Hekemian & Co [Member]
Related Party Transaction [Line Items]
Leasing commissions and reimbursement of operating expenses	$ 167,000	130,000		515,000	385,000
Insurance commissions	105,000	110,000		164,000	181,000
Additional services	94,000	0		6,388,000	236,500
Asset management fees	318,000	525,000		1,108,000	1,587,000
Robert S. Hekemian, Jr. [Member]
Related Party Transaction [Line Items]
Trustee fees and related interest payable in stock units	150,000	118,000		429,000	350,000
Allan Tubin [Member]
Related Party Transaction [Line Items]
Trustee fees and related interest payable in stock units	10,000		$ 8,000	30,000	23,000
David Hekemian [Member]
Related Party Transaction [Line Items]
Trustee fees and related interest payable in stock units	$ 13,000	$ 15,000		$ 43,000	$ 42,000
Minimum [Member]
Related Party Transaction [Line Items]
Asset management fees percentage rate				4.00%
Maximum [Member]
Related Party Transaction [Line Items]
Asset management fees percentage rate				5.00%