Financial Instruments and Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012	Jun. 30, 2012	Sep. 30, 2011
Financial Instruments and Fair Value Measurments
Cash and cash equivalents, Estimated Fair Value	$ 60,972	$ 61,829
Investments in deferred compensation program, Estimated Fair Value	7,898	7,316
Note receivable from municipality, Estimated Fair Value	2,517	0
Treasury lock, Estimated Fair Value	546	0
Short-term borrowings, Estimated Fair Value	(35,144)	(329)
Long-term debt, including current portion, Estimated Fair Value	(587,443)	(443,827)
Cash and cash equivalents, Carrying Cost	60,972	61,829	39,903	74,539
Investments in deferred compensation program, Carrying Cost	7,898	7,316
Note receivable from municipality, Carrying Cost	2,064	0
Treasury lock, Carrying Cost	546	0
Short-term borrowings, Carrying Cost	(35,144)	(329)
Long-term debt, including current portion, Carrying Cost	$ (550,000)	$ (391,875)