CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Apr. 25, 2020	Apr. 27, 2019
Statement of Cash Flows [Abstract]
Interest Paid, Excluding Capitalized Interest, Operating Activities	$ 8,510	$ 7,474
Gain (Loss) on Extinguishment of Debt	12,504	0
Extinguishment of 0.75% senior notes	(167,003)	0
Proceeds From Redemption Of Discount on Debt Instrument [Abstract]	20,040	0
Proceeds from Derivative Instrument, Financing Activities	341	0
Purchase of warrants	(397)	0
Cash flows from operating activities:
Net (loss) income	(32,418)	14,279
Adjustments to reconcile net (loss) income to net cash used in operating activities:
Depreciation and amortization	45,871	46,341
Non-cash lease expense	7,921	7,390
Deferred income tax (benefit) provision	(8,710)	5,579
Stock-based compensation	2,322	3,479
Provision for bad debt (recovery), net	118	(10,311)
Gain on sale of fixed assets	(1,788)	(6,738)
Amortization of debt discount	4,341	4,932
Amortization of debt issuance costs and other	951	985
Goodwill impairment charge	53,264	0
Change in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	(54,134)	(76,297)
Contract assets, net	(13,763)	(84,031)
Other current assets and inventories	(11,337)	(16,994)
Other assets	2,019	37,323
Income taxes receivable/payable	11,518	730
Accounts payable	80,319	18,300
Accrued liabilities, insurance claims, operating lease liabilities, and other liabilities	11,171	(1,089)
Net cash provided by (used in) operating activities	85,161	(56,122)
Cash flows from investing activities:
Capital expenditures	(20,701)	(45,768)
Proceeds from sale of assets	2,400	7,362
Net cash used in investing activities	(18,301)	(38,406)
Proceeds from Long-term Lines of Credit	675,000	0
Cash flows from financing activities:
Principal payments on senior credit agreement, including term loans	(5,625)	0
Exercise of stock options	242	106
Restricted stock tax withholdings	(326)	(841)
Net cash provided by (used in) financing activities	522,272	(735)
Net increase (decrease) in cash and equivalents and restricted cash	589,132	(95,263)
Cash, cash equivalents and restricted cash at beginning of period	59,869	134,151
Cash, cash equivalents and restricted cash at end of period	649,001	38,888
SUPPLEMENTAL DISCLOSURE OF OTHER CASH FLOW ACTIVITIES AND NON-CASH INVESTING AND FINANCING ACTIVITIES:
Cash paid for taxes, net	52	814
Purchases of capital assets included in accounts payable or other accrued liabilities at period end	2,933	8,054
Gain (Loss) on Extinguishment of Debt	$ 12,504	0
0.75% Convertible Senior Notes Due 2021 [Member]
Debt Instrument, Interest Rate, Stated Percentage	0.75%
Gain (Loss) on Extinguishment of Debt	$ 12,500
Adjustments to reconcile net (loss) income to net cash used in operating activities:
Amortization of debt discount	4,300	$ 4,900
Cash flows from financing activities:
Principal payments on senior credit agreement, including term loans	(147,000)
SUPPLEMENTAL DISCLOSURE OF OTHER CASH FLOW ACTIVITIES AND NON-CASH INVESTING AND FINANCING ACTIVITIES:
Gain (Loss) on Extinguishment of Debt	$ 12,500