Summary of Significant Accounting Policies - Allowance of Uncollectible Amounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Allowance for Uncollectible Accounts [Roll Forward]
Balance at Beginning of Year	$ 36,295	$ 40,228	$ 31,639
Additions Charged to Costs and Expenses	13,180	14,482	13,209
Add: Discounts on Purchased Receivables	753	1,380	1,314
Deduct: Net Accounts Receivable Written-Off	24,034	19,795	5,934
Balance at End of Year	$ 26,194	$ 36,295	$ 40,228