Derivatives - Schedule of Forward Currency Contract, Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Offsetting Derivative Assets [Abstract]
Net amounts presented in the Consolidated Statements of Financial Condition	$ 11,636	$ 29,490
Collateral (Received) Pledged	0	(650)
Macquarie Bank Limited
Offsetting Derivative Assets [Abstract]
Gross Amount of Recognized Assets	3,274	5,695
Gross Amount of Recognized (Liabilities)	(1,651)	(5,469)
Net amounts presented in the Consolidated Statements of Financial Condition	1,623	226
Collateral (Received) Pledged	0	0
Net Amounts	1,623	226
SMBC Capital Markets, Inc.
Offsetting Derivative Assets [Abstract]
Gross Amount of Recognized Assets	10,482	31,486
Gross Amount of Recognized (Liabilities)	(469)	(2,222)
Net amounts presented in the Consolidated Statements of Financial Condition	10,013	29,264
Collateral (Received) Pledged	0	0
Net Amounts	$ 10,013	$ 29,264