Income Taxes - Components of Federal and State Income Taxes Included in the Consolidated Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Current Income Taxes —
Federal	$ 11,744	$ 0	$ (10)
State	1,386	12,214	8,699
Deferred Income Taxes —
Federal	106,801	137,025	90,970
State	44,602	(32,610)	15,023
Total Income Taxes	$ 164,533	$ 116,629	$ 114,682