Investments in Unconsolidated Entities - Unconsolidated Entities (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated entities	$ 964	$ 4,464
Total equity of unconsolidated entities	939,286	724,884	$ 593,171	$ 538,754
Total outstanding borrowings of unconsolidated entities	0	12,708
Equity in income of unconsolidated entities	521	594	$ 347
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Total equity of unconsolidated entities	$ 1,564	$ 7,316