Revenue (Schedule of Accounts Receivable) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Contract With Customer Asset [Line Items]
Total billed receivables	$ 441,964	$ 485,227
Current unbilled receivables (contract assets)	325,007	270,479
Total accounts receivable	766,971	755,706
Less: Allowance for uncollectible amounts	(6,961)	(5,847)
Total accounts receivable, net	760,010	749,859
Trade Accounts Receivable [Member]
Contract With Customer Asset [Line Items]
Billed receivables	441,007	434,287
Other (Chinese Financial Institutions) [Member]
Contract With Customer Asset [Line Items]
Billed receivables	$ 957	$ 50,940