USE OF SPECIAL PURPOSE ENTITIES AND VARIABLE INTEREST ENTITIES - Narrative (Details) $ in Thousands	Jun. 14, 2021 USD ($) tranche subsidiary
Variable Interest Entity [Line Items]
Number of wholly-owned subsidiaries \| subsidiary	2
Equity interest retained	$ 96,250
Proceeds from issuance of long-term debt allocated to acquire additional loan obligations	$ 330,300
Period to acquire additional loan obligations from closing date	180 days
Collateralized loan obligation leverage ratio (as a percent)	0.83
Collateralized Loan Obligations - LFT CRE 2021-FL1, Ltd.
Variable Interest Entity [Line Items]
Number of tranches of CLO notes issued \| tranche	8
Aggregate principal of CLO notes	$ 903,800
Portfolio of loan obligations securing the notes	$ 669,700
Reinvestment period for collateralized loan obligation	2 years 6 months
Proceeds from issuance of collateralized loan obligations	$ 1,000,000
Notional amount of residual interest in collateralized loan obligation portfolio	166,200
Collateralized Loan Obligations - LFT CRE 2021-FL1, Ltd. - Investment Grade
Variable Interest Entity [Line Items]
Aggregate principal of CLO notes	833,800
Collateralized Loan Obligations - LFT CRE 2021-FL1, Ltd. - Below Investment Grade
Variable Interest Entity [Line Items]
Aggregate principal of CLO notes	70,000
Collateralized Loan Obligations - Hunt CRE 2017-FL1, Ltd. and Hunt CRE 2018-FL2, Ltd.
Variable Interest Entity [Line Items]
Outstanding notes redeemed	388,200
Write off of deferred debt issuance cost	$ 1,700

Collateralized Loan Obligation Leverage Ratio

No definition available.

Name:	oaks_CollateralizedLoanObligationLeverageRatio
Namespace Prefix:	oaks_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Face Amount, Residual Interest

+ References

No definition available.

+ Details

Name:	oaks_DebtInstrumentFaceAmountResidualInterest
Namespace Prefix:	oaks_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Debt Instrument, Number of Tranches

+ References

No definition available.

+ Details

Name:	oaks_DebtInstrumentNumberOfTranches
Namespace Prefix:	oaks_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of Newly Formed Subsidiaries

+ References

No definition available.

+ Details

Name:	oaks_NumberOfNewlyFormedSubsidiaries
Namespace Prefix:	oaks_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Period to Acquire Additional Loan Obligations from Closing Date

+ References

No definition available.

+ Details

Name:	oaks_PeriodToAcquireAdditionalLoanObligationsFromClosingDate
Namespace Prefix:	oaks_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Proceeds from Issuance of Long-Term Debt Allocated To Acquire Additional Loan Obligations

+ References

No definition available.

+ Details

Name:	oaks_ProceedsFromIssuanceOfDebtSecuritiesAllocatedToAcquireAdditionalLoanObligations
Namespace Prefix:	oaks_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reinvestment Period for Collateralized Loan Obligation

+ References

No definition available.

+ Details

Name:	oaks_ReinvestmentPeriodForCollateralizedLoanObligation
Namespace Prefix:	oaks_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Variable Interest Entity, Qualitative and Quantitative Information, Equity Interest

+ References

No definition available.

+ Details

Name:	oaks_VariableInterestEntityQualitativeAndQuantitativeInformationEquityInterest
Namespace Prefix:	oaks_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of assets pledged to secure a debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ Details

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

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585

+ Details

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

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

- Definition

Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

+ 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 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=oaks_CollateralizedLoanObligationsLFTCRE2021FL1LtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oaks_CollateralizedLoanObligationsLFTCRE2021FL1LtdInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oaks_CollateralizedLoanObligationsLFTCRE2021FL1LtdBelowInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oaks_CollateralizedLoanObligationsHuntCRE2017FL1LtdAndHuntCRE2018FL2LtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: