Transition Period Comparative Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								6 Months Ended		12 Months Ended
	Jan. 25, 2020	Oct. 26, 2019	Jul. 27, 2019	Apr. 27, 2019	Jan. 26, 2019	Oct. 27, 2018	Jul. 28, 2018	Apr. 28, 2018	Jan. 27, 2018	Jan. 28, 2017	Jan. 25, 2020	Jan. 26, 2019	Jul. 29, 2017
Accounting Policies [Abstract]
Revenues	$ 737,603	$ 884,115	$ 884,221	$ 833,743	$ 748,619	$ 848,237	$ 799,470	$ 731,375	$ 1,411,348	$ 1,500,355	$ 3,339,682	$ 3,127,700	$ 3,066,880
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	633,203	724,378	720,382	701,767	633,279	687,164	642,376	599,573	1,141,480	1,176,361	2,779,730	2,562,392	2,404,734
General and administrative									124,930	118,395	254,590	269,140	239,231
Depreciation and amortization									85,053	70,252	187,556	179,603	147,906
Total									1,351,463	1,365,008	3,221,876	3,011,135	2,791,871
Interest expense, net									(19,560)	(18,248)	(50,859)	(44,369)	(37,364)
Other income, net									6,225	1,946	11,665	15,842	12,780
Income before income taxes									46,550	119,045	78,536	88,038	250,425
(Benefit) provision for income taxes									(22,285)	44,332	21,321	25,131	93,208
Net income	$ (11,189)	$ 24,229	$ 29,896	$ 14,279	$ (12,054)	$ 27,830	$ 29,900	$ 17,231	$ 68,835	$ 74,713	$ 57,215	$ 62,907	$ 157,217
Earnings per common share:
Basic earnings per common share (in dollars per share)	$ (0.35)	$ 0.77	$ 0.95	$ 0.45	$ (0.38)	$ 0.89	$ 0.96	$ 0.55	$ 2.22	$ 2.37	$ 1.82	$ 2.01	$ 5.01
Diluted earnings per common share (in dollars per share)	$ (0.35)	$ 0.76	$ 0.94	$ 0.45	$ (0.38)	$ 0.87	$ 0.94	$ 0.53	$ 2.15	$ 2.32	$ 1.80	$ 1.97	$ 4.92
Shares used in computing earnings per common share:
Basic (in shares)									31,059,140	31,480,660	31,498,474	31,250,376	31,351,367
Diluted (in shares)									32,054,945	32,180,923	31,821,782	31,990,168	31,984,731