Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits - beginning balance	$ 58,638	$ 52,683	$ 32,792
Decrease resulting from prior period tax positions	(2,867)	(631)	(721)
Decrease resulting from a lapse in statute of limitations	(6,188)	0	0
Increase resulting from current period tax positions	8,214	6,586	20,612
Unrecognized tax benefits - ending balance	57,797	58,638	52,683
Less: deferred federal and state income tax benefits	(12,137)	(12,314)	(11,063)
Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year	$ 45,660	$ 46,324	$ 41,620