Financial Instruments and Fair Value Measurements (Narrative) (Details) - Measurement Input, Discount Rate [Member]	Jun. 30, 2025	Sep. 30, 2024
Long-Term Debt [Member] | Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Interest rate used to measure long-term debt	4.3	4.5
Long Term Notes Receivable from Municipalities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Interest rate used to measure municipal notes	3.4	2.7
Investments in Short-Term Time Deposits [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Interest rate used to measure short-term time deposits	5.3	6.8