Financial Instruments and Fair Value Measurements (Narrative) (Details) - Measurement Input, Discount Rate [Member]	Dec. 31, 2021	Sep. 30, 2021
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	1.9	1.6
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	1.2	1.3
Interest rate used to measure promissory notes	1.0	1.0
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	3.2	3.3