Long-Term Debt and Bank Facility Borrowings - Company's Debt (Detail) - USD ($) $ in Thousands		Sep. 30, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Long-term debt, carrying Amount		$ 122,805	$ 153,447
Current maturities of long-term debt, carrying Amount	[1]	13,000	33,000
Long-term debt	[1]	109,805	120,447
Long-term debt, fair value	[2]	123,500	154,000
Current maturities of long-term debt, fair value	[1],[2]	13,000	33,000
Long-term portion of debt, fair value	[1],[2]	110,500	121,000
Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility borrowings, carrying Amount		0	61,500
Credit facility borrowings, fair value	[2]	0	61,500
Term Loan
Debt Instrument [Line Items]
Long-term debt, carrying Amount	[3]	122,805	91,947
Long-term debt, fair value	[2],[3]	$ 123,500	$ 92,500

[1] On December 4, 2019, the Company refinanced its five-year term loan and the revolving credit facility with the execution of the fifth amended and restated revolving credit facility agreement. As of September 30, 2019, the Company has classified $37.5 million of its revolving credit facility borrowings as long term debt and repaid it on December 4, 2019 using proceeds provided by the fifth amended and restated revolving credit facility agreement.

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

[3] Carrying amounts are net of unamortized debt issuance costs of $0.7 million as of September 30, 2020 and $0.6 million as of September 30, 2019.