Revenue from Contracts with Customers - Contract Balances - Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Billed Receivables	$ 264,942	$ 234,745
Unbilled Receivables	210,795	203,896
Receivables Gross	475,737	438,641
Allowance for doubtful accounts	(6,454)	(4,978)	$ (4,218)
Net receivables	469,283	433,663
Accounts Receivable, net , noncurrent	(42,641)	(45,716)
Accounts receivable, net	426,642	387,947
Expense, Allowance for Credit Loss	1,675	1,475
Write-off	$ (199)	$ (715)