Debt - Summary of Long-Term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 597,000	$ 600,000
Less unamortized deferred financing costs	(4,354)	(4,712)
Less unamortized original issue discount	(4,074)	(4,409)
Less current portion	(6,000)	(6,000)
Long-term debt—less current portion and unamortized deferred financing costs	582,572	584,879
2022 Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	597,000	600,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Less unamortized deferred financing costs	$ (800)	$ (900)

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount, after accumulated amortization, of debt discount.

+ References

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt classified as noncurrent. Excludes lease obligation.

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