Revenue (Schedule of Accounts Receivable) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
Contract With Customer Asset [Line Items]
Total billed receivables	$ 530,127	$ 485,227
Current unbilled receivables (contract assets)	308,776	270,479
Total accounts receivable	838,903	755,706
Less: Allowance for uncollectible amounts	(7,126)	(5,847)
Total accounts receivable, net	831,777	749,859
Trade Accounts Receivable [Member]
Contract With Customer Asset [Line Items]
Billed receivables	478,207	434,287
Other (Chinese Financial Institutions) [Member]
Contract With Customer Asset [Line Items]
Billed receivables	$ 51,920	$ 50,940