Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Accounts Receivable
Accounts receivable, Total	$ 174,427	$ 163,740
Commercial
Accounts Receivable
Accounts receivable, Total	153,265	146,049
U.S. Government and prime contractors
Accounts Receivable
Accounts receivable, Total	$ 21,162	$ 17,691