Financial Instruments and Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Cash and cash equivalents, Carrying Cost	$ 54,590	$ 48,556	$ 69,456	$ 61,829
Note receivable from municipality, Carrying Cost	14,735	8,114
Short-term borrowings, Carrying Cost	(10,000)	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	15,163	6,718
Short-term borrowings, Estimated Fair Value	(10,000)	0
Long-term debt, including current portion, Estimated Fair Value	$ (614,588)	$ (588,297)