Accounts Receivable, Contract Assets, and Contract Liabilities - Customer Credit Concentration (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 31, 2021	Jul. 25, 2020	Jul. 31, 2021	Jul. 25, 2020	Jan. 30, 2021
Concentration Risk
Amount	$ 929,120		$ 929,120		$ 858,123
% of Total	100.00%	100.00%	100.00%	100.00%
Customer Concentration Risk | Trade Accounts Receivable and Costs and Estimated Earnings | Verizon Communications Inc.
Concentration Risk
Amount	$ 333,700		$ 333,700		$ 389,900
% of Total			30.90%		37.40%
Customer Concentration Risk | Trade Accounts Receivable and Costs and Estimated Earnings | Lumen Technologies
Concentration Risk
Amount	163,400		$ 163,400		$ 173,500
% of Total			15.10%		16.60%
Customer Concentration Risk | Trade Accounts Receivable and Costs and Estimated Earnings | Comcast Corporation
Concentration Risk
Amount	$ 131,500		$ 131,500		$ 131,700
% of Total			12.20%		12.60%