Financial Instruments and Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012
Cash and cash equivalents, Carrying Cost	$ 56,665	$ 48,556	$ 54,658	$ 61,829
Note receivable from municipality, Carrying Cost	14,978	8,114
Short-term borrowings, Carrying Cost	(21,000)	0
Long-term debt, including current portion, Carrying Cost	(584,000)	(550,000)
Fair Value, Inputs, Level 2 [Member]
Note receivable from municipality, Estimated Fair Value	15,782	6,718
Short-term borrowings, Estimated Fair Value	(21,000)	0
Long-term debt, including current portion, Estimated Fair Value	$ (621,175)	$ (588,297)