Income Taxes - Summary of Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Current:
Federal	$ 16,184	$ 31,986	$ 18,966
State	3,434	5,492	3,108
Foreign	0	6	0
Current total	19,618	37,484	22,074
Deferred:
Federal	(19,171)	5,376	3,341
State	(3,859)	365	387
Foreign	0	0	0
Deferred total	(23,030)	5,741	3,728
Income tax (benefit) expense	$ (3,412)	$ 43,225	$ 25,802