Summary of Significant Accounting Policies - Other Assets (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 05, 2015	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets, net of accumulated amortization		$ 96,647	$ 106,063
Total Managed Equity REITs
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and shares received from related party	$ 167,764
Other assets, net of accumulated amortization	$ 193,806
Total Managed Equity REITs | Up C Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortization of other assets		$ 9,416	$ 9,416	$ 9,416