Summary of Significant Accounting Policies - Allowance of Uncollectible Amounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Allowance for Uncollectible Accounts [Roll Forward]
Balance at Beginning of Year	$ 26,194	$ 36,295	$ 40,228
Additions Charged to Costs and Expenses	19,195	13,180	14,482
Add: Discounts on Purchased Receivables	863	753	1,380
Deduct: Net Accounts Receivable Written-Off	29,153	24,034	19,795
Balance at End of Year	$ 17,099	$ 26,194	$ 36,295