Fair Value of Financial Instruments - Carrying Value and Estimated Fair Value of Company's Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Participations sold	$ (24,356)	$ (27,064)
Commercial Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Participations sold	(24,356)	(27,064)
Carrying Value
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash and cash equivalents	241,619	343,106
Carrying Value \| Level III
Accounts, Notes, Loans and Financing Receivable [Line Items]
Subordinate loan held-for-sale	7,500	0
Secured debt arrangements, net	(5,183,837)	(4,150,268)
Participations sold	(24,356)	(27,064)
Carrying Value \| Level III \| Secured Debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured term loans, net	(766,159)	(768,325)
Carrying Value \| Level III \| Senior Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured term loans, net	(494,445)	(494,051)
Carrying Value \| Level III \| 2022 Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes	(344,899)	(343,117)
Carrying Value \| Level III \| 2023 Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes	(228,991)	(226,862)
Carrying Value \| Level III \| Commercial Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,176,149	7,012,312
Carrying Value \| Level III \| Subordinate Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	753,711	844,948
Estimate of Fair Value Measurement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash and cash equivalents	241,619	343,106
Estimate of Fair Value Measurement \| Level III
Accounts, Notes, Loans and Financing Receivable [Line Items]
Subordinate loan held-for-sale	7,500	0
Secured debt arrangements, net	(5,183,837)	(4,150,268)
Participations sold	(24,596)	(27,064)
Estimate of Fair Value Measurement \| Level III \| Secured Debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured term loans, net	(743,198)	(782,995)
Estimate of Fair Value Measurement \| Level III \| Senior Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior secured term loans, net	(374,200)	(489,175)
Estimate of Fair Value Measurement \| Level III \| 2022 Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes	(344,600)	(347,552)
Estimate of Fair Value Measurement \| Level III \| 2023 Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes	(231,150)	(231,150)
Estimate of Fair Value Measurement \| Level III \| Commercial Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,136,674	6,945,038
Estimate of Fair Value Measurement \| Level III \| Subordinate Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 748,812	$ 725,906

Real Estate Owned, Subordinate Loans, Held For Sale, Net

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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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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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