Supplemental Consolidating Financial Statements - Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 26, 2013	Oct. 27, 2012
Revenues [Abstract]
Contract revenues	$ 512,720	$ 323,286
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	410,119	257,066
General and administrative	43,075	28,824
Depreciation and amortization	23,552	15,311
Intercompany charges (income), net	0	0
Total	476,746	301,201
Interest income (expense), net	(6,886)	(4,197)
Other income, net	2,012	1,614
INCOME BEFORE INCOME TAXES	31,100	19,502
PROVISION (BENEFIT) FOR INCOME TAXES	12,440	7,641
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	18,660	11,861
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0
NET INCOME	18,660	11,861
Foreign currency translation gain	(60)	2
COMPREHENSIVE INCOME (LOSS)	18,600	11,863
Parent
Revenues [Abstract]
Contract revenues	0	0
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	0	0
General and administrative	11,237	8,409
Depreciation and amortization	854	740
Intercompany charges (income), net	(13,976)	(9,925)
Total	(1,885)	(776)
Interest income (expense), net	(1,888)	(776)
Other income, net	3	0
INCOME BEFORE INCOME TAXES	0	0
PROVISION (BENEFIT) FOR INCOME TAXES	0	0
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	0	0
EQUITY IN EARNINGS OF SUBSIDIARIES	18,660	11,861
NET INCOME	18,660	11,861
Foreign currency translation gain	(60)	2
COMPREHENSIVE INCOME (LOSS)	18,600	11,863
Issuer
Revenues [Abstract]
Contract revenues	0	0
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	0	0
General and administrative	226	146
Depreciation and amortization	0	0
Intercompany charges (income), net	0	0
Total	226	146
Interest income (expense), net	(4,994)	(3,420)
Other income, net	0	0
INCOME BEFORE INCOME TAXES	(5,220)	(3,566)
PROVISION (BENEFIT) FOR INCOME TAXES	(2,087)	(1,397)
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	(3,133)	(2,169)
EQUITY IN EARNINGS OF SUBSIDIARIES	21,793	14,030
NET INCOME	18,660	11,861
Foreign currency translation gain	(60)	2
COMPREHENSIVE INCOME (LOSS)	18,600	11,863
Subsidiary Guarantors
Revenues [Abstract]
Contract revenues	509,430	319,025
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	407,695	253,544
General and administrative	28,945	17,616
Depreciation and amortization	21,621	13,286
Intercompany charges (income), net	14,110	10,272
Total	472,371	294,718
Interest income (expense), net	(4)	(1)
Other income, net	1,945	1,565
INCOME BEFORE INCOME TAXES	39,000	25,871
PROVISION (BENEFIT) FOR INCOME TAXES	15,600	10,136
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	23,400	15,735
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0
NET INCOME	23,400	15,735
Foreign currency translation gain	0	0
COMPREHENSIVE INCOME (LOSS)	23,400	15,735
Non-Guarantor Subsidiaries
Revenues [Abstract]
Contract revenues	3,290	4,261
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	2,424	3,522
General and administrative	2,667	2,653
Depreciation and amortization	1,077	1,285
Intercompany charges (income), net	(134)	(347)
Total	6,034	7,113
Interest income (expense), net	0	0
Other income, net	64	49
INCOME BEFORE INCOME TAXES	(2,680)	(2,803)
PROVISION (BENEFIT) FOR INCOME TAXES	(1,073)	(1,098)
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	(1,607)	(1,705)
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0
NET INCOME	(1,607)	(1,705)
Foreign currency translation gain	(60)	2
COMPREHENSIVE INCOME (LOSS)	(1,667)	(1,703)
Eliminations and Reclassifications
Revenues [Abstract]
Contract revenues	0	0
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Intercompany charges (income), net	0	0
Total	0	0
Interest income (expense), net	0	0
Other income, net	0	0
INCOME BEFORE INCOME TAXES	0	0
PROVISION (BENEFIT) FOR INCOME TAXES	0	0
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	0	0
EQUITY IN EARNINGS OF SUBSIDIARIES	(40,453)	(25,891)
NET INCOME	(40,453)	(25,891)
Foreign currency translation gain	120	(4)
COMPREHENSIVE INCOME (LOSS)	$ (40,333)	$ (25,895)