Accounts Receivable, Net - Accounts Receivables Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts Receivable Net Current [Abstract]
Trade accounts receivable	$ 200,721	$ 159,992
Unbilled revenue, at net realizable value	84,753	60,684
Total accounts receivable	285,474	220,676
Allowance for doubtful accounts	(13,693)	(13,389)
Accounts receivable, net	$ 271,781	$ 207,287

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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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 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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