BORROWINGS - Types of Repurchase Agreements (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Repurchase Agreements
Amount outstanding	$ 1,237,661,000	$ 804,811,000
Weighted average interest rate, percentage	1.37%	1.07%
Market value of collateral held	$ 1,309,061,643	$ 876,121,505
Agency
Repurchase Agreements
Amount outstanding	$ 1,215,217,000	$ 755,221,000
Weighted average interest rate, percentage	1.34%	0.97%
Market value of collateral held	$ 1,273,735,621	$ 790,190,232
Non-Agency
Repurchase Agreements
Amount outstanding	$ 2,750,000	$ 7,313,000
Weighted average interest rate, percentage	3.13%	2.39%
Market value of collateral held	$ 4,575,603	$ 12,784,707
Multi-Family
Repurchase Agreements
Amount outstanding	$ 19,694,000	$ 42,277,000
Weighted average interest rate, percentage	2.99%	2.52%
Market value of collateral held	$ 30,750,419	$ 73,146,566

This is the weighted average interest rate during the reporting period as a result of repurchase agreements.

No definition available.

Name:	oaks_RepurchaseAgreementsWeightedAverageInterestRate
Namespace Prefix:	oaks_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value of collateral permitted, by contact or custom, to be sold or re-pledged.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

+ Details

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

- Definition

Carrying value, as of the balance sheet date, of securities sold under agreements to repurchase where the transferor maintains effective control over the assets, accounting for them as secured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(m)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 10
-Section 55
-Paragraph 51
-URI http://asc.fasb.org/extlink&oid=77903054&loc=d3e101761-111710

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=oaks_AgencyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=oaks_NonAgencyRmbsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MultifamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: