CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jul. 25, 2015	Apr. 25, 2015	Jan. 24, 2015	Oct. 25, 2014	Jul. 26, 2014	Apr. 26, 2014	Jan. 25, 2014	Oct. 26, 2013	Jul. 25, 2015	Jul. 26, 2014	Jul. 27, 2013
REVENUES:
Contract revenues	$ 578,479	$ 492,363	$ 441,081	$ 510,389	$ 482,071	$ 426,284	$ 390,518	$ 512,720	$ 2,022,312	$ 1,811,593	$ 1,608,612
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	446,114	388,239	355,429	403,468	387,221	350,352	327,353	410,119	1,593,250	1,475,045	1,300,416
General and administrative (including stock-based compensation expense of $13.9 million, $12.6 million, and $9.9 million, respectively)									178,700	161,858	145,771
Depreciation and amortization									96,044	92,772	85,481
Total									1,867,994	1,729,675	1,531,668
Interest expense, net									(27,025)	(26,827)	(23,334)
Other income, net									8,291	11,228	4,589
Income before income taxes									135,584	66,319	58,199
Provision (benefit) for income taxes:
Current									50,016	32,664	25,281
Deferred									1,244	(6,323)	(2,270)
Total provision for income taxes									51,260	26,341	23,011
Net income	$ 33,827	$ 20,258	$ 9,432	$ 20,807	$ 16,489	$ 7,895	$ (3,067)	$ 18,660	$ 84,324	$ 39,978	$ 35,188
Earnings per common share:
Basic earnings (loss) per common share (in dollars per share)	$ 1.00	$ 0.59	$ 0.28	$ 0.61	$ 0.49	$ 0.23	$ (0.09)	$ 0.56	$ 2.48	$ 1.18	$ 1.07
Diluted earnings (loss) per common share (in dollars per share)	$ 0.97	$ 0.58	$ 0.27	$ 0.59	$ 0.47	$ 0.23	$ (0.09)	$ 0.54	$ 2.41	$ 1.15	$ 1.04
Shares used in computing earnings per common share:
Basic (in shares)									34,045,481	33,773,158	33,012,595
Diluted (in shares)									35,026,688	34,816,381	33,782,187