Income Taxes Narrative (Detail) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Income Tax Contingency [Line Items]
Income tax provision (benefit)	$ 1,560,000	$ 1,117,000	$ (1,550,000)	$ 1,910,000
Reductions in unrecognized tax benefits from expiration	600,000
Tax benefit recognized for research and development tax credit	900,000		900,000
Minimum
Income Tax Contingency [Line Items]
Anticipated unrecognized tax benefit reduction during next twelve months	$ 1,300,000		$ 1,300,000