CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 25, 2020	Jul. 31, 2021	Jul. 25, 2020
Income Statement [Abstract]
Contract revenues	$ 787,568	$ 823,921	$ 1,515,065	$ 1,638,244
Costs of earned revenues, excluding depreciation and amortization	651,367	657,953	1,271,378	1,338,159
General and administrative	64,730	67,357	131,740	133,243
Depreciation and amortization	38,462	44,129	77,542	90,001
Goodwill impairment charge			0	53,264
Total	754,559	769,439	1,480,660	1,614,667
Interest expense, net	(9,334)	(7,853)	(15,211)	(20,310)
(Loss) gain on debt extinguishment	0	(458)	(62)	12,046
Other income, net	986	3,097	3,703	4,214
Income before income taxes	24,661	49,268	22,835	19,527
Provision for income taxes	6,496	12,244	3,772	14,921
Net income	$ 18,165	$ 37,024	$ 19,063	$ 4,606
Earnings per common share:
Basic earnings per common share (in dollars per share)	$ 0.60	$ 1.17	$ 0.62	$ 0.15
Diluted earnings per common share (in dollars per share)	$ 0.59	$ 1.15	$ 0.61	$ 0.14
Shares used in computing earnings per common share:
Basic (in shares)	30,431,143	31,750,547	30,553,381	31,677,012
Diluted (in shares)	30,872,506	32,128,098	31,085,985	31,947,346