Customer Concentration and Revenue Information - Customer Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2022	May 01, 2021
Concentration Risk
Contract revenues	$ 876,300	$ 727,497
Customer Concentration Risk | Revenue Benchmark
Concentration Risk
Contract revenues	$ 876,300	$ 727,500
% of Total	100.00%	100.00%
Customer Concentration Risk | Revenue Benchmark | Telecommunications
Concentration Risk
Contract revenues	$ 778,900	$ 639,700
% of Total	88.90%	87.90%
Customer Concentration Risk | Revenue Benchmark | Underground facility locating
Concentration Risk
Contract revenues	$ 70,900	$ 65,000
% of Total	8.10%	8.90%
Customer Concentration Risk | Revenue Benchmark | Electrical and gas utilities and other
Concentration Risk
Contract revenues	$ 26,500	$ 22,800
% of Total	3.00%	3.20%
Five Unnamed Customers | Customer Concentration Risk | Revenue Benchmark
Concentration Risk
% of Total	67.30%	68.20%