Accounts Receivable - Net Accounts Receivable and Billings in Excess of Costs on Uncompleted Contracts (Details) - USD ($) $ in Thousands	Oct. 01, 2017	Oct. 02, 2016
Accounts Receivable - Net and Revenue Recognition
Billed	$ 376,287	$ 364,287
Unbilled	404,899	356,147
Contract retentions	39,840	29,135
Total accounts receivable – gross	821,026	749,569
Allowance for doubtful accounts	(32,259)	(35,233)
Total accounts receivable – net	788,767	714,336
Billings in excess of costs on uncompleted contracts	$ 117,499	$ 88,223