Name:	frevsob_MortgageLoansOnRealEstateExtendedAmount
Namespace Prefix:	frevsob_
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Period Type:	instant

Amount of annual principal payment for debt instrument.

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Period Type:	instant

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
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Face (par) amount of debt instrument at time of issuance.

Name:	us-gaap_DebtInstrumentFaceAmount
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Amount of the fee that accompanies borrowing money under the debt instrument.

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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.

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Name:	us-gaap_DebtInstrumentLineItems
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Balance Type:	na
Period Type:	duration

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

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Name:	us-gaap_DebtInstrumentMaturityDate
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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

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Period Type:	duration

Amount of the required periodic payments applied to interest.

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Balance Type:	debit
Period Type:	duration

The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy.

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

Average amount borrowed under the credit facility during the period.

No definition available.

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

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Name:	us-gaap_LinesOfCreditCurrent
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of cash outflow for short-term and long-term debt. Excludes payment of lease obligation.

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

This element represents those amounts set aside for the repair and replacement of real or personal property in the foreseen future. Such amount may be funded from sales revenue (for example; timeshare sales) or operating revenues; in a lump sum or installments (such as monthly); as per internal policy (for example: hotel operators), as required by contractual agreement (for example: sales contract); or by the terms of debt agreements.

No definition available.

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

The portion of the carrying amount of short-term borrowings outstanding as of the balance sheet date which accrues interest at a set, unchanging rate.

No definition available.

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

The portion of the carrying amount of short-term borrowings outstanding as of the balance sheet date, which accrues interest at a rate subject to change from time to time.

No definition available.

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

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Namespace Prefix:
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Balance Type:
Period Type:

Name:	srt_StatementGeographicalAxis=frevsob_RockawayMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

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