Debt and Preferred Equity Investments - Schedule of Carrying Value of Debt and Preferred Equity Investment Portfolio by Year of Origination and Risk Rating (Details) $ in Thousands	Sep. 30, 2025 USD ($) investment	Dec. 31, 2024 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2024	$ 0
2023	0
2022	0
Prior	171,412
Carrying value	$ 171,412	$ 303,726
Number of investments, nonperforming | investment	1
Debt and preferred equity investments	$ 171,412	303,726
Total floating rate
Financing Receivable, Credit Quality Indicator [Line Items]
Debt and preferred equity investments	131,080	117,160
Alternative Strategy Portfolio | Total floating rate
Financing Receivable, Credit Quality Indicator [Line Items]
Debt and preferred equity investments	53,500
1 - Low Risk Assets - Low probability of loss
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	0
Prior	20,000
Carrying value	20,000	156,720
2 - Watch List Assets - Higher potential for loss
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	0
Prior	151,412
Carrying value	151,412	147,006
3 - High Risk Assets - Loss more likely than not
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	0
Prior	0
Carrying value	$ 0	$ 0