Financial Instruments and Fair Value Measurements (Narrative) (Details) $ in Thousands	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)
Investments in Short-Term Time Deposits [Member] | Measurement Input, Discount Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate used to measure short-term time deposits	4.9	5.7
Long Term Notes Receivable From Municipalities [Member] | Measurement Input, Discount Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate used to measure municipal notes	1.8	1.7
Long-Term Debt [Member] | Measurement Input, Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate used to measure long-term debt	2.5	2.5
Cross Currency Interest Rate Swaps [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cross currency interest rate swaps, assets	$ 13,474	$ 24,758
Cross Currency Interest Rate Swaps [Member] | Other Assets [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cross currency interest rate swaps, assets	13,474	24,758
Cross Currency Interest Rate Swaps [Member] | Other Liabilities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cross currency interest rate swaps, liabilities