Valuation and Qualifying Accounts (Details) (Allowance for doubtful accounts receivables, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009	Sep. 30, 2008
Allowance for doubtful accounts receivables
Movement in valuation and qualifying accounts
Balance at Beginning of Period	$ 1,129	$ 1,116	$ 1,310	$ 1,354	$ 1,339
Charges (credits) to Expense	235	54	263	470	100
Deductions	(115)	(41)	(457)	(514)	(85)
Balance at End of Period	$ 1,249	$ 1,129	$ 1,116	$ 1,310	$ 1,354