CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jan. 27, 2018	Jan. 25, 2020	Jan. 26, 2019	Jul. 29, 2017
Cash flows from operating activities:
Net income	$ 68,835	$ 57,215	$ 62,907	$ 157,217
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	85,053	187,556	179,603	147,906
Non-cash lease expense	0	30,043	0	0
Non-cash lease expense	(19,665)	9,261	8,523	18,233
Stock-based compensation	13,277	10,034	20,187	20,805
Provision for bad debt (recovery), net	201	(6,540)	17,071	199
Gain on sale of fixed assets	(7,217)	(14,879)	(19,390)	(14,866)
Loss on debt extinguishment	0	76	0	0
Amortization of debt discount	9,170	20,112	19,103	17,610
Amortization of debt issuance costs and other	1,736	4,023	3,686	3,323
Excess tax benefit from share-based awards	0	0	0	(8,385)
Change in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	50,955	(195,796)	(30,750)	(33,068)
Contract assets, net	16,982	(35,888)	(149,828)	(27,773)
Other current assets and inventories	(67)	(6,960)	(15,842)	(13,232)
Other assets	1,630	41,068	(25,110)	2,064
Income taxes receivable/payable	(6,716)	(84)	10,357	(13,189)
Accounts payable	(21,503)	(2,141)	20,064	977
Accrued liabilities, insurance claims, operating lease liabilities, and other liabilities	(32,138)	(39,101)	23,866	(1,378)
Capital expenditures	160,533	57,999	124,447	256,443
Proceeds from sale of assets
Capital expenditures	(87,839)	(120,574)	(164,963)	(201,197)
Proceeds from sale of assets	11,808	19,045	22,949	16,029
Cash paid for acquisitions, net of cash acquired	0	0	(20,917)	(26,070)
Proceeds from acquisition working capital adjustment	0	0	0	1,825
Other investing activities	0	306	1,576	666
Net cash used in investing activities	(76,031)	(101,223)	(161,355)	(208,747)
Principal payments on senior credit agreement, including term loans
Proceeds from borrowings on senior credit agreement, including term loans	0	475,000	423,188	707,000
Principal payments on senior credit agreement, including term loans	(9,625)	(480,625)	(331,250)	(685,563)
Debt financing costs	0	0	(7,275)	(70)
Repurchase of common stock	(16,875)	0	0	(62,909)
Extinguishment of 0.75% senior notes	0	(25,000)	0	0
Redemption discount on convertible debt, net of costs	0	675	0	0
Settlement of convertible note hedge	0	388	0	0
Buyback of warrants	0	(301)	0	0
Exercise of stock options	745	503	871	1,449
Restricted stock tax withholdings	(12,581)	(1,698)	(4,657)	(10,767)
Excess tax benefit from share-based awards	0	0	0	8,385
Net cash provided by (used in) financing activities	(38,336)	(31,058)	80,877	(42,475)
Net decrease in cash and equivalents and restricted cash	46,166	(74,282)	43,969	5,221
Cash, cash equivalents and restricted cash at beginning of period	44,016	134,151	90,182	38,795
Cash, cash equivalents and restricted cash at end of period	90,182	59,869	134,151	44,016
Supplemental disclosure of other cash flow activities and non-cash investing and financing activities:
Cash paid for interest	7,748	26,655	22,312	16,505
Cash paid for taxes, net	4,749	12,017	6,396	88,060
Purchases of capital assets included in accounts payable or other accrued liabilities at period end	$ 1,634	$ 8,814	$ 6,795	$ 21,978