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Accounts Receivable Concentration Risk (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Oct. 27, 2018	Oct. 28, 2017	Jan. 27, 2018	Oct. 27, 2018	Oct. 28, 2017	Jan. 28, 2018
Concentration Risk
Accounts receivable, net	$ 849,769		$ 318,684	$ 849,769		$ 630,400
Concentration risk percentage	100.00%	100.00%		100.00%	100.00%
Customer Concentration Risk | Trade Accounts Receivable and Costs and Estimated Earnings | Comcast Corporation
Concentration Risk
Accounts receivable, net	$ 166,600		$ 166,500	$ 166,600
Concentration risk percentage			24.50%	16.90%
Customer Concentration Risk | Trade Accounts Receivable and Costs and Estimated Earnings | AT&T Inc.
Concentration Risk
Accounts receivable, net	338,700		$ 98,200	$ 338,700
Concentration risk percentage			14.40%	34.30%
Customer Concentration Risk | Trade Accounts Receivable and Costs and Estimated Earnings | CenturyLink, Inc.
Concentration Risk
Accounts receivable, net	142,800		$ 126,000	$ 142,800
Concentration risk percentage			18.50%	14.50%
Customer Concentration Risk | Trade Accounts Receivable and Costs and Estimated Earnings | AT&T Inc.
Concentration Risk
Accounts receivable, net	$ 102,700		$ 79,200	$ 102,700
Concentration risk percentage			11.60%	10.40%

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Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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