Company's Debt (Detail) - USD ($) $ in Thousands		Jun. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Long-term debt, carrying Amount		$ 109,912	$ 75,717
Long-term debt	[1]	94,612	65,717
Long-term debt, fair value	[2]	110,300	76,300
Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility borrowings, carrying Amount		41,500
Long-term portion of revolving credit facility borrowings, carrying Amount	[3]	33,700
Credit facility borrowings, fair value	[2]	41,500
Long-term portion of revolving credit facility borrowings, fair value	[2],[3]	33,700
Term Loan
Debt Instrument [Line Items]
Long-term debt, carrying Amount	[4]	68,412	75,717
Long-term debt	[4]	60,912	65,717
Long-term debt, fair value	[2],[4]	68,800	76,300
Long-term portion of term loan, fair value	[2],[4]	$ 61,300	$ 66,300

[1] See Note 14 – Subsequent events

[2] The face amount of the Company’s variable rate long-term debt approximates fair value.

[3] On July 2, 2018, the Company refinanced its five-year term loan and the revolving credit facility with the execution of the fourth amended and restated revolving credit facility agreement. (See Note 14—Subsequent Events). As of June 30, 2018, the Company has classified $33.7 million of its revolving credit facility borrowings as long term debt and repaid it on July 3, 2018 using $33.7 million of proceeds provided by the fourth amended and restated revolving credit facility agreement

[4] Carrying amounts are net of unamortized debt issuance costs of $0.4 million as of June 30, 2018 and $0.6 million as of September 30, 2017.