Revenue (Schedule of Accounts Receivable) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Contract With Customer Asset [Line Items]
Total billed receivables	$ 321,575	$ 322,119
Current unbilled receivables (contract assets)	256,740	204,596
Total accounts receivable	578,315	526,715
Less: Allowance for uncollectible amounts	(3,141)	(3,664)
Total accounts receivable, net	575,174	523,051
Trade Accounts Receivable [Member]
Contract With Customer Asset [Line Items]
Billed receivables	311,302	298,951
Other (Chinese Financial Institutions) [Member]
Contract With Customer Asset [Line Items]
Billed receivables	$ 10,273	$ 23,168