Accounts Receivable (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jan. 27, 2018	Jan. 26, 2019	Jan. 28, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bad debt expense, net	$ (38)	$ 27
Contract with Customer, Asset, Gross	369,472	215,849	$ 57,800
Accounts Receivable, Net, Current	318,684	625,258	630,400
Trade accounts receivable	300,271	331,903
Unbilled Contracts Receivable	0	283,463
Retainage	19,411	10,831
Total	319,682	626,197
Less: allowance for doubtful accounts	(998)	(939)
Accounts receivable, net	318,700	625,258	630,400
Contract liabilities	6,480	15,125
Contract with Customer, Asset, Net	$ 362,992	200,724
Windstream
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net		45,000
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Accounting Standards Update 2014-09 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contract with Customer, Asset, Gross		(283,463)
Accounts Receivable, Net, Current		283,463	$ 311,700
Windstream
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Noncurrent		$ 24,800

Contract Receivable Retainage and Other Receivables

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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.

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Amounts due from customers or clients, more than one year from the balance sheet date, for goods or services that have been delivered or sold in the normal course of business.

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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.

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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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