Accounts Receivable, net - Components of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Sep. 26, 2021	Dec. 31, 2020
Receivables [Abstract]
Billed receivables	$ 170,005	$ 227,787
Unbilled receivables	358,345	360,552
Less allowance for credit losses	(3,643)	(2,828)
Total accounts receivables, net	$ 524,707	$ 585,511

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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- Definition

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

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