Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015
Income Tax Disclosure [Line Items]
Income tax provisions	$ 1,358	$ 1,480	$ 2,650	$ 2,950
Effective tax rates	62.20%	32.70%	44.30%	30.70%
U.S. federal statutory tax rate	35.00%	35.00%	35.00%	35.00%
Discrete tax benefit			$ 200	$ 200
Permanent tax differences	$ 2,300		4,300
Unrecognized tax benefits excluding interest and penalties that would impact effective tax rate	$ 1,100		$ 1,100		$ 900
Intersect ENT [Member]
Income Tax Disclosure [Line Items]
Gain on sale of investment		$ 500		$ 500