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Transactions with Controlled Companies - Strategic Chemical Solutions Corp. (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 31, 2025	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024	Feb. 18, 2026
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Interest Income		$ 581,932	$ 671,109	$ 770,312
Administrative agent fees		887	763	730
Total Other Income		10,555	28,949	79,397
Realized (Loss) Gain		(223,719)	(518,682)	(417,443)
Interest Receivable		17,350	25,144
Reportable Legal Entities \| Subsidiaries \| Strategic Chemical Solutions Corp
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Interest Income		2,826	2,775	1,990
Administrative agent fees		6	0	0
Total Other Income		6	0	0
Additions		0	6,000	0
Interest Income Capitalized as PIK		1,405	2,638	1,545
Repayment of Loan Receivable		0	2,300	0
Interest Receivable		8	8
Other Receivables		$ 197	221
Strategic Chemical Solutions Corp \| Reportable Legal Entities \| Subsidiaries
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Ownership interest		99.96%
Prospect Administration \| Reportable Legal Entities \| Subsidiaries \| Strategic Chemical Solutions Corp
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Realized (Loss) Gain		$ (66,219)	0	0
Reimbursement of Legal, Tax, etc		$ 4	$ 74	$ 0
Term Loan A \| Strategic Chemical Solutions Corp
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Principal amount					$ 0
Realized loss	$ 35,568
Term Loan B \| Strategic Chemical Solutions Corp
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Principal amount					$ 0
Realized loss	$ 30,651