Fair Value of Financial Instruments - Carrying Value and Estimated Fair Value of Company's Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Carrying Value
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash and cash equivalents	$ 194,287	$ 225,438
Carrying Value \| Level III
Accounts, Notes, Loans and Financing Receivable [Line Items]
Secured debt arrangements, net	(5,513,945)	(5,538,476)
Debt related to real estate owned, held for investment, net	(278,837)	(161,586)
Carrying Value \| Level III \| Secured Debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans, net	(755,441)	(759,150)
Carrying Value \| Level III \| Senior Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans, net	(496,233)	(495,637)
Carrying Value \| Level III \| Commercial Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial mortgage loans, net	7,456,389	7,925,359
Carrying Value \| Level III \| Subordinate Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial mortgage loan, held for sale	374,222	432,734
Estimate of Fair Value Measurement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash and cash equivalents	194,287	225,438
Estimate of Fair Value Measurement \| Level III
Accounts, Notes, Loans and Financing Receivable [Line Items]
Secured debt arrangements, net	(5,513,945)	(5,538,476)
Debt related to real estate owned, held for investment, net	(278,837)	(161,586)
Estimate of Fair Value Measurement \| Level III \| Secured Debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans, net	(748,643)	(754,197)
Estimate of Fair Value Measurement \| Level III \| Senior Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans, net	(446,250)	(418,750)
Estimate of Fair Value Measurement \| Level III \| Commercial Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial mortgage loans, net	7,373,832	7,813,304
Estimate of Fair Value Measurement \| Level III \| Subordinate Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial mortgage loan, held for sale	$ 374,222	$ 432,458

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

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- 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
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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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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- Definition

Fair value portion of contractual arrangement with a lender under which borrowings can be made up to a specific amount at any point in time.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 825
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- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

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-Topic 820
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- Definition

Fair value portion of notes payable.

+ References

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