Revenue from Contracts with Customers - Schedule of Contract Balances, Receivables (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Sep. 30, 2025
Revenue from Contract with Customer [Abstract]
Billed	$ 355,327	$ 327,721
Unbilled	300,794	246,600
Accounts receivable, gross	656,121	574,321
Less: allowance for doubtful accounts	(7,720)	(7,964)
Net receivables	648,401	566,357
Less: long-term receivables	(28,444)	(37,209)
Short-term receivables	$ 619,957	$ 529,148

Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

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Amounts due for billed services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the Company and, at a minimum, one other party. An example would be amounts billed to customers under contracts or programs but not paid as of the balance sheet date.

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Unbilled amounts due for services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the entity and, at a minimum, one other party. An example would be amounts associated with contracts or programs where the recognized revenue for performance thereunder exceeds the amounts billed under the terms thereof as of the date of the balance sheet.

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