CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 24, 2020	Oct. 26, 2019	Oct. 24, 2020	Oct. 26, 2019
Income Statement [Abstract]
Contract revenues	$ 810,256	$ 884,115	$ 2,448,500	$ 2,602,079
Costs of earned revenues, excluding depreciation and amortization	658,355	724,378	1,996,514	2,146,527
General and administrative	62,628	69,875	195,871	193,613
Depreciation and amortization	42,313	47,356	132,313	140,941
Goodwill impairment charge			53,264	0
Total	763,296	841,609	2,377,962	2,481,081
Interest expense, net	(4,710)	(13,128)	(25,020)	(38,239)
Gain on debt extinguishment			12,046	0
Other income, net	3,708	1,407	7,921	11,111
Income before income taxes	45,958	30,785	65,485	93,870
Provision for income taxes	12,032	6,556	26,953	25,466
Net income	$ 33,926	$ 24,229	$ 38,532	$ 68,404
Earnings per common share:
Basic earnings per common share (in dollars per share)	$ 1.06	$ 0.77	$ 1.21	$ 2.17
Diluted earnings per common share (in dollars per share)	$ 1.05	$ 0.76	$ 1.20	$ 2.15
Shares used in computing earnings per common share:
Basic (in shares)	31,878,583	31,502,543	31,744,199	31,480,759
Diluted (in shares)	32,425,300	31,826,845	32,106,661	31,811,505