Interest on trustee fees.

No definition available.

Name:	ras_InterestOnTrusteeFees
Namespace Prefix:	ras_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Maximum ownership percentage of outstanding common shares and preferred shares to exempt equity ownership limit.

+ References

No definition available.

+ Details

Name:	ras_MaximumOwnershipPercentageOfOutstandingCommonSharesAndPreferredSharesToExemptEquityOwnershipLimit
Namespace Prefix:	ras_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum ownership percentage of outstanding common shares to exempt common share ownership limit.

+ References

No definition available.

+ Details

Name:	ras_MaximumOwnershipPercentageOfOutstandingCommonSharesToExemptCommonShareOwnershipLimit
Namespace Prefix:	ras_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Reduction of outstanding common shares holdings percentage.

+ References

No definition available.

+ Details

Name:	ras_ReductionOfOutstandingCommonSharesHoldingsPercentage
Namespace Prefix:	ras_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Related party transaction agreement date.

+ References

No definition available.

+ Details

Name:	ras_RelatedPartyTransactionAgreementDate
Namespace Prefix:	ras_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date of maturity or expiration of arrangements with a related party (for example, but not limited to, leasing and debt arrangements between related parties), in CCYY-MM-DD format.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
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_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 http://asc.fasb.org/extlink&oid=115205541&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_RelatedPartyTransactionsByRelatedPartyAxis=ras_BallardSpahrLLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ras_CooperationAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ras_LetterAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ras_HighlandCapitalManagementLPMember
Namespace Prefix:
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Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended
	May 11, 2018	Apr. 06, 2018	Mar. 31, 2019	Mar. 31, 2018	Mar. 30, 2018
Ballard Spahr LLP
Related Party Transaction [Line Items]
Trustee fee paid				$ 32
Interest on trustee fee				$ 1
Libby Frischer Family Partnership
Related Party Transaction [Line Items]
Maximum common shares ownership percentage that would exempt common share ownership limit					12.50%
LFFP and Mr. Frischer \| Cooperation Agreement
Related Party Transaction [Line Items]
Related party transaction agreement date		Apr. 06, 2018
Maximum common shares and preferred shares ownership percentage that would exempt ownership limit		15.00%
LFFP and Mr. Frischer \| Letter Agreement
Related Party Transaction [Line Items]
Related party transaction agreement date	May 11, 2018
Maximum common shares and preferred shares ownership percentage that would exempt ownership limit	20.00%
Highland Capital Management, L. P.
Related Party Transaction [Line Items]
Related party transaction agreement date			May 26, 2017
Related party transaction standstill date			May 26, 2019
Reduction of outstanding common shares holdings percentage			4.90%