Contract Balances and Performance Obligation - Receivables (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Billed	$ 195,159	$ 206,714
Unbilled	154,365	127,651
Receivables Gross	349,524	334,365
Less: allowance for doubtful accounts	(4,753)	(2,568)
Net receivables	344,771	331,797
Less: long-term receivables	(41,213)	(34,370)
Short-term receivables	$ 303,558	$ 297,427

Receivables, Gross

No definition available.

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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.

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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.

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

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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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