Long-term Debt (Schedule of Long-term Debt) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Long-term debt balance	$ 425,246
Total long-term debt	425,249	443,743
Less: current portion	(18,374)	(18,493)
Long-term debt, less current portion	406,875	425,250
Designated as Hedging Instrument [Member] | Accumulated Other Comprehensive Earnings [Member]
Fair value hedge adjustment for unrecognized discontinued hedge gains	(781)	(1,011)
Designated as Hedging Instrument [Member] | Current and Long-Term Debt [Member]
Fair value hedge adjustment for unrecognized discontinued hedge gains	3	70
Designated as Hedging Instrument [Member]
Fair value hedge adjustment for unrecognized discontinued hedge gains	(778)	(941)
2008 Term Loan [Member] | Medium-term Notes [Member]
Long-term debt balance	64,375	71,875
Variable interest rate	1.78%
Maturity date	Oct. 01, 2013
Series B Notes [Member] | Notes Payable to Banks [Member]
Long-term debt balance	100,000	100,000
Interest rate	5.63%
Maturity date	Oct. 01, 2013
Series C Notes [Member] | Notes Payable to Banks [Member]
Long-term debt balance	50,000	50,000
Interest rate	5.92%
Maturity date	Oct. 01, 2015
Series D Notes [Member] | Notes Payable to Banks [Member]
Long-term debt balance	100,000	100,000
Interest rate	6.39%
Maturity date	Oct. 01, 2018
Series E Notes [Member] | Notes Payable to Banks [Member]
Long-term debt balance	57,000	57,000
Interest rate	7.81%
Maturity date	Apr. 03, 2016
Series F Notes [Member] | Notes Payable to Banks [Member]
Long-term debt balance	43,000	43,000
Interest rate	8.24%
Maturity date	Apr. 03, 2019
Senior Notes, Series A [Member] | Notes Payable to Banks [Member]
Long-term debt balance	10,714	21,429
Interest rate	6.39%
Maturity date	Oct. 15, 2011
Term Notes [Member] | Secured Debt [Member]
Long-term debt balance	$ 157	$ 369
Interest rate	5.95%
Maturity date	Jun. 30, 2012