Financial Instruments and Fair Value Measurements (Narrative) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Financial liability on recurring basis	$ 0	$ 0
Investments in Short-Term Time Deposits [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Interest rate used to estimate fair value	5.30%	6.90%
Long Term Notes Receivable From Municipalities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Interest rate used to estimate fair value	2.60%	2.20%
Borrowings [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Interest rate used to estimate fair value	2.40%	1.90%