Revenue and Accounts Receivable - Rollforward of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 40,840	$ 49,993	$ 64,471
Current period provisions	24,843	22,353	16,576
Write-offs charged against allowance	(26,165)	(33,595)	(32,885)
Recoveries of amounts previously written off	1,730	2,089	1,831
Mississippi recovery of uncollectible accounts	(4,192)
Ending balance	$ 37,056	$ 40,840	$ 49,993