Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 25, 2020	Jan. 26, 2019
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 327,267	$ 327,267
Accumulated Amortization	187,322	166,142
Intangible Assets, Net	139,945	161,125
UtiliQuest
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,700	4,700
Intangible Assets, Net	$ 4,700	4,700
Customer relationships
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Lives (Years)	10 years 2 months 12 days
Gross Carrying Amount	$ 312,017	312,017
Accumulated Amortization	178,411	157,691
Intangible Assets, Net	$ 133,606	154,326
Trade names
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Lives (Years)	7 years 10 months 24 days
Gross Carrying Amount	$ 10,350	10,350
Accumulated Amortization	8,732	8,312
Intangible Assets, Net	$ 1,618	2,038
Non-compete agreements
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Lives (Years)	15 days
Gross Carrying Amount	$ 200	200
Accumulated Amortization	179	139
Intangible Assets, Net	$ 21	$ 61