Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2016
Income Tax Disclosure [Line Items]
Income tax provisions	$ 533,000	$ 2,926,000	$ 3,315,000	$ 5,440,000
Effective tax rates	42.50%	42.80%	48.50%	42.30%
U.S. federal statutory tax rate	35.00%	35.00%	35.00%	35.00%
State income tax reserve reversals related to statutory filing			$ 200,000
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
Expiring Stock Option Awards [Member]
Income Tax Disclosure [Line Items]
Discrete tax expense			$ 300,000