Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2019	Oct. 01, 2018	Sep. 30, 2018
Accounts receivable
Billed	$ 127,406		$ 156,948
Unbilled			242,877
Allowance for doubtful accounts	(1,392)		(1,324)
Total accounts receivables	126,014		398,501
Less unbilled amounts not currently due--commercial customers			(6,134)
Current accounts receivable	126,014	$ 155,624	392,367
Trade receivables sold to a financial institution	31,100
U.S. federal government contracts
Accounts receivable
Billed	$ 60,300		$ 80,500

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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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Amount of allowance for credit loss on accounts receivable, classified as current.

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Amounts due for billed services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the Company and, at a minimum, one other party. An example would be amounts billed to customers under contracts or programs but not paid as of the balance sheet date.

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Amount of decrease from sale of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time and other income.

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Amount to be collected within one year of the balance sheet date (or one operating cycle, if longer) from customers in accordance with the contractual provisions of long-term contracts or programs including amounts billed and unbilled as of the balance sheet date.

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Amount received for services rendered and products shipped, but not yet billed, for non-contractual agreements due within one year or the normal operating cycle, if longer.

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