Customer Concentration and Revenue Information - Trade Receivable Risk (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 30, 2021	Oct. 24, 2020	Jul. 25, 2020	Apr. 25, 2020	Jan. 25, 2020	Oct. 26, 2019	Jul. 27, 2019	Apr. 27, 2019	Jan. 30, 2021	Jan. 25, 2020	Jan. 26, 2019
Concentration Risk [Line Items]
Amount	$ 750,665	$ 810,256	$ 823,921	$ 814,322	$ 737,603	$ 884,115	$ 884,221	$ 833,743	$ 3,199,165	$ 3,339,682	$ 3,127,700
% of Total									100.00%	100.00%	100.00%
Customer Concentration Risk | Revenue Benchmark
Concentration Risk [Line Items]
Amount									$ 3,199,200	$ 3,339,700	$ 3,127,700
% of Total									100.00%	100.00%	100.00%
Telecommunications | Customer Concentration Risk | Revenue Benchmark
Concentration Risk [Line Items]
Amount									$ 2,851,600	$ 3,031,900	$ 2,855,800
% of Total									89.10%	90.80%	91.30%
Underground facility locating | Customer Concentration Risk | Revenue Benchmark
Concentration Risk [Line Items]
Amount									$ 229,600	$ 204,500	$ 182,700
% of Total									7.20%	6.10%	5.80%
Electrical and gas utilities and other | Customer Concentration Risk | Revenue Benchmark
Concentration Risk [Line Items]
Amount									$ 118,000	$ 103,300	$ 89,200
% of Total									3.70%	3.10%	2.90%