Revenue (Schedule of Accounts Receivable) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Sep. 30, 2022
Contract With Customer Asset [Line Items]
Total billed receivables	$ 342,990	$ 368,769
Current unbilled receivables (contract assets)	258,266	245,117
Total accounts receivable	601,256	613,886
Less: Allowance for uncollectible amounts	(4,203)	(3,922)
Total accounts receivable, net	597,053	609,964
Trade Accounts Receivable [Member]
Contract With Customer Asset [Line Items]
Billed receivables	335,010	359,364
Other (Chinese Financial Institutions) [Member]
Contract With Customer Asset [Line Items]
Billed receivables	$ 7,980	$ 9,405