Accounts Receivable - Net - Net Accounts Receivable and Billings in Excess of Costs on Uncompleted Contracts (Details) - USD ($) $ in Thousands	Sep. 29, 2019	Sep. 30, 2018
Accounts Receivable - Net and Revenue Recognition
Billed	$ 522,256	$ 464,062
Unbilled	300,035	267,739
Total accounts receivable – gross	822,291	731,801
Allowance for doubtful accounts	(53,571)	(37,580)
Total accounts receivable – net	$ 768,720	$ 694,221

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Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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