Income Taxes - Income Tax Provision (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Summary of income tax provisions
Current provision	$ 16,017	$ 13,874	$ 10,307
Deferred (benefit) provision	(1,791)	(1,378)	2,679
Deferred benefit of state net operating loss carryforwards, net of federal effect, recognized based on change in tax regulations	(1,216)
Federal provision	11,485	8,517	12,047
State provision	380	2,170	924
Foreign provision	1,145	1,809	15
Income Tax Expense (Benefit)	$ 13,010	$ 12,496	$ 12,986