Supporting Financial Information - Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 10,280	$ 11,911
Less: Allowance for doubtful accounts	0	0
Accounts receivable, net	10,280	11,911
Billed Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	10,066	11,862
Unbilled Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 214	$ 49