Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income tax provisions	$ 1,055,000	$ 1,362,000	$ 2,782,000	$ 2,514,000
Effective tax rates	67.50%	62.40%	49.80%	42.00%
U.S. federal statutory tax rate	35.00%	35.00%	35.00%	35.00%
Unrecognized tax benefits excluding interest and penalties that would impact effective tax rate	$ 1,200,000		$ 1,200,000		$ 1,200,000
Undistributed earnings in foreign subsidiaries	$ 0		$ 0		$ 0