Debt and Preferred Equity Investments - Schedule of Roll Forward of our Total Allowance for Loan Losses (Details) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2024 USD ($) loan	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) loan	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Loan loss reserve activity
Balance at beginning of year			$ 13,520	$ 6,630	$ 6,630
Current period provision for loan loss	$ 0	$ 0	0	$ 6,890	6,890
Balance at end of period	$ 13,520		$ 13,520		$ 13,520
Number of financing receivables on non-accrual without allowance for loan loss \| loan	1		1
Alternative Strategy Portfolio (3) \| Total floating rate
Loan loss reserve activity
Financing receivable on non-accrual without allowance	$ 49,800		$ 49,800

Financing Receivable, Nonaccrual, No Allowance, Number

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- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

+ Details

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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.

+ Details

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- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

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- Definition

Amortized cost of financing receivable on nonaccrual status with no allowance for credit loss. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

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