Equity (Schedule of Earnings per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Equity [Abstract]
Numerator - Net income (loss)	$ 11,697	$ (9,335)	$ 14,523	$ (23,564)
Less: Undistributed earnings allocated to participating securities	(94)	0	(118)	0
Undistributed earnings allocated to common shareholders for basic net income (loss) per share	11,603	(9,335)	14,405	(23,564)
Undistributed earnings allocated to common shareholders for diluted net income (loss) per share	$ 11,603	$ (9,335)	$ 14,405	$ (23,564)
Denominator:
Denominator for basic net income (loss) per share - weighted average shares outstanding	26,310	23,529	26,142	23,577
Dilutive options outstanding, unvested stock units and ESPP	332	0	290	0
Denominator for diluted net income (loss) per share - adjusted weighted average shares outstanding	26,642	23,529	26,432	23,577
Net loss per basic share (in dollars per share)	$ 0.44	$ (0.40)	$ 0.55	$ (1.00)
Net loss per diluted share (in dollars per share)	$ 0.44	$ (0.40)	$ 0.54	$ (1.00)
Weighted average antidilutive options, unvested restricted stock units and warrants excluded from the computation	1,869	3,587	2,265	3,384
Average market price of common stock	$ 5.66	$ 4.72	$ 5.16	$ 4.31