Shareholders’ Equity - Issuances/Repurchases (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2025 USD ($) vesting_installment shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General and administrative expense	$ 42,497	$ 43,743	$ 36,019
Equity based compensation expenses	$ 178,470	$ 187,278	$ 150,845
Managing Director | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares	35,928	25,314	18,000
2016 Plan | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of installments | vesting_installment	5
General and administrative expense	$ 600	$ 600	$ 464
Adjustment related to tax withholding for share based compensation	903	1,136	734
2016 Plan | Officers and Employees | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity based compensation expenses	$ 2,782	$ 2,705	$ 2,662