Receivables (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Components of receivables:
Amounts billed	$ 927,500	$ 1,110,042
Unbilled receivables and other	1,090,918	937,552
Retentions receivable	39,587	68,069
Total receivables, net	2,058,005	2,115,663
Other information about receivables:
Amounts due from the United States federal government, included above, net of advanced billings	212,969	235,203
Claims receivable	$ 26,169	$ 26,061

Other Information About Receivables [Abstract]

No definition available.

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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 billed to customers under long-term contracts or programs that have been withheld because of retainage provisions in a contract.

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Amount of billed or unbilled claims or other similar items subject to uncertainty concerning their determination or ultimate realization under long-term contracts.

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Amount receivable from related parties classified as other, due within one year or the normal operating cycle, if longer.

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The total amount due to the entity within one year of the balance sheet date (or one operating cycle, if longer) from outside sources, including trade accounts receivable, notes and loans receivable, as well as any other types of receivables, net of allowances established for the purpose of reducing such receivables to an amount that approximates their net realizable value.

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Unbilled amounts due for 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 entity and, at a minimum, one other party. An example would be amounts associated with contracts or programs where the recognized revenue for performance thereunder exceeds the amounts billed under the terms thereof as of the date of the balance sheet.

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