LOANS - Corporate Debt Held for Investment (Details) - Corporate Loans - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Beginning balance	$ 1,968,991	$ 2,239,930
Originations & advances	171,697	1,572,718
Sales and transfers		(1,205,965)
Principal payments	(174,238)	(661,941)
Amortization & accretion of (premium) discounts	1,825	12,617
Allowance for loan losses
Beginning allowance	(27,920)	(39,552)
Current period (allowance) reversal	(608)	11,632
Ending allowance	(28,528)	(27,920)
Net carrying value	1,967,667	1,968,991
First lien loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Beginning balance	1,391,217	1,489,125
Originations & advances	154,396	1,506,705
Sales and transfers		(1,122,275)
Principal payments	(74,251)	(492,884)
Amortization & accretion of (premium) discounts	885	9,120
Allowance for loan losses
Beginning allowance	(17,341)	(18,767)
Current period (allowance) reversal	(701)	1,426
Ending allowance	(18,042)	(17,341)
Net carrying value	1,471,546	1,391,217
Second lien loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Beginning balance	577,774	750,805
Originations & advances	17,301	66,013
Sales and transfers		(83,690)
Principal payments	(99,987)	(169,057)
Amortization & accretion of (premium) discounts	940	3,497
Allowance for loan losses
Beginning allowance	(10,579)	(20,785)
Current period (allowance) reversal	93	10,206
Ending allowance	(10,486)	(10,579)
Net carrying value	$ 496,121	$ 577,774

SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Excluding Loan Loss Allowance

No definition available.

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- Definition

Amount of decrease in investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from collection of principal.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Footnote 6
-Subsection 29

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Footnote 6))
-URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014

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- Definition

The net increase(decrease) in interest income during the period representing the allocation of deferred loan origination fees less deferred loan origination costs using the effective interest method over the term of the debt arrangement to which they pertain taking into account the effect of prepayments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124402152&loc=d3e8622-111531

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

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- Definition

Amount, excluding accrued interest, of allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

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- Definition

Amount of expense (reversal of expense) for expected credit loss on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Column G))
-URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014

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- Definition

Amount of decrease in investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Footnote 6))
-URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014

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- Definition

Amount of addition to investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, classified as other.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Footnote 6))
-URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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