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, 2025	Sep. 30, 2024	Sep. 30, 2023
Current Income Taxes —
Federal		$ 42,089	$ 6,453	$ 11,744
State		12,186	5,899	1,386
Deferred Income Taxes —
Federal		90,881	894	106,801
State		30,393	(3,504)	44,602
Total Income Taxes	[1]	$ 175,549	$ 9,742	$ 164,533

[1] The Company considers this line to be a significant expense.