Fair Value of Financial Instruments - Carrying Value and Estimated Fair Value of Company's Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Participations sold	$ 0	$ (25,130)
Commercial Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Participations sold	0	(25,130)
Carrying Value
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash and cash equivalents	331,533	222,030
Carrying Value \| Level III
Accounts, Notes, Loans and Financing Receivable [Line Items]
Secured debt arrangements, net	(5,316,853)	(5,296,825)
Debt related to real estate owned, held for investment, net	(160,611)	(160,294)
Participations sold	0	(25,130)
Carrying Value \| Level III \| Secured Debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans, net	(762,706)	(763,813)
Carrying Value \| Level III \| Senior Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans, net	(495,040)	(494,844)
Carrying Value \| Level III \| 2023 Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes	(222,467)	(229,361)
Carrying Value \| Level III \| Commercial Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	7,879,205	8,121,109
Carrying Value \| Level III \| Subordinate Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	592,863	560,881
Estimate of Fair Value Measurement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash and cash equivalents	331,533	222,030
Estimate of Fair Value Measurement \| Level III
Accounts, Notes, Loans and Financing Receivable [Line Items]
Secured debt arrangements, net	(5,316,853)	(5,296,825)
Debt related to real estate owned, held for investment, net	(160,611)	(160,294)
Participations sold	0	(25,130)
Estimate of Fair Value Measurement \| Level III \| Secured Debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans, net	(671,528)	(731,709)
Estimate of Fair Value Measurement \| Level III \| Senior Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans, net	(346,250)	(400,950)
Estimate of Fair Value Measurement \| Level III \| 2023 Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes	(217,600)	(225,366)
Estimate of Fair Value Measurement \| Level III \| Commercial Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	7,818,304	8,083,410
Estimate of Fair Value Measurement \| Level III \| Subordinate Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 590,409	$ 558,740

Debt Related To Real Estate Owned, Held For Investment, Net, Fair Value Disclousre

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

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Fair value portion of notes payable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20,22)
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The aggregate amount of the participation liability at the end of the accounting period.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=99377297&loc=d3e10013-112621

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