Income Taxes - Summary of Income Tax Contingencies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Reconciliation of gross unrecognized tax benefits for uncertain tax positions
Balance at beginning of year	$ 4,063	$ 2,591	$ 3,830
Additions for current year tax positions	476	1,377	203
Additions for prior year tax positions	331	266	154
Reductions of prior year tax positions	(12)	(20)	(1,104)
Settlements	(640)	(151)	(492)
Balance at end of year	$ 4,218	$ 4,063	$ 2,591