Accounts Receivable - Accounts Receivable Net Classification (Details) - USD ($) $ in Thousands	Jan. 25, 2020	Jan. 26, 2019
Receivables [Abstract]
Trade accounts receivable	$ 355,805	$ 331,903
Unbilled accounts receivable	453,353	283,463
Retainage	12,669	10,831
Total	821,827	626,197
Less: allowance for doubtful accounts	(4,582)	(939)
Accounts Receivable, Net	$ 817,245	$ 625,258

Contract Receivable Retainage and Other Receivables

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- Definition

For unclassified balance sheet, amounts due from customers or clients for goods or services that have been delivered or sold in the normal course of business.

+ References

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- Definition

For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

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- Definition

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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- Definition

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

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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