Company's Debt (Detail) - USD ($) $ in Thousands		Sep. 30, 2018		Sep. 30, 2017
Debt Instrument [Line Items]
Long-term debt, carrying Amount		$ 100,780		$ 75,717
Current maturities of long-term debt, carrying Amount		9,000		10,000
Long-term debt		91,780		65,717
Long-term debt, fair value		101,500	[1]	76,300
Current maturities of long-term debt, fair value		9,000	[1]	10,000
Long-term portion of debt, fair value		92,500	[1]	66,300
Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility borrowings, carrying Amount		1,500
Credit facility borrowings, fair value	[1]	1,500
Term Loan
Debt Instrument [Line Items]
Long-term debt, carrying Amount	[2]	99,280		75,717
Long-term debt, fair value	[2]	$ 100,000	[1]	$ 76,300

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

[2] Carrying amounts are net of unamortized debt issuance costs of $0.7 million as of September 30, 2018 and $0.6 million as of September 30, 2017.