Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Current federal	$ 0	$ 0	$ 0
Current state	1,896	4,859	1,126
Deferred federal	18,997	47,239	20,331
Deferred state	3,065	1,173	89
Total expense from income taxes	$ 23,958	$ 53,271	$ 21,546