Income Taxes Narrative (Detail) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Income Taxes [Line Items]
Income tax provision (benefit)	$ (129,000)	$ (659,000)	$ (3,799,000)	$ (359,000)
Income tax benefit from U.S. federal research and development tax credits			900,000
Income tax benefit from reduction in uncertain tax position as a result of the lapse in statutes of limitations				1,400,000
Anticipated unrecognized tax benefit reduction during next twelve months	$ 1,500,000		$ 1,500,000