Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Income Taxes [Line Items]
Income tax provision (benefit)	$ (659,000)	$ 1,035,000	$ (359,000)	$ 2,023,000
Tax benefit driven by reductions in uncertain tax positions as a result of lapse in statutes of limitation	1,400,000		1,400,000
Anticipated unrecognized tax benefit reduction during next twelve months	$ 2,500,000		$ 2,500,000