Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Accounts Receivable
Accounts receivable, Total	$ 144,082	$ 158,715
Commercial
Accounts Receivable
Accounts receivable, Total	121,924	137,553
U.S. Government and prime contractors
Accounts Receivable
Accounts receivable, Total	$ 22,158	$ 21,162