Stockholders' Equity - Summary of RSU Activities (Detail) (USD $)	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Unvested, Beginning Balance	1,016,624
Number of Shares, Granted	1,166,303
Number of Shares, Vested	(513,188)
Number of Shares, Forfeited	(32,529)
Number of Shares, Unvested, Ending Balance	1,637,210	1,016,624
Weighted Average Grant Date Fair Value, Beginning Balance	$ 2.23
Weighted Average Grant Date Fair Value, Granted	$ 2.65	$ 2.15	$ 4.12	$ 2.08
Weighted Average Grant Date Fair Value, Vested	$ 2.64
Weighted Average Grant Date Fair Value, Forfeited	$ 2.23
Weighted Average Grant Date Fair Value, Ending Balance	$ 2.40	$ 2.23