Supplemental Consolidating Financial Statements Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 26, 2013	Jan. 28, 2012	Jan. 26, 2013	Jan. 28, 2012
Revenues [Abstract]
Contract revenues	$ 369,326	$ 267,407	$ 692,613	$ 586,981
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	301,516	220,239	558,582	475,426
General and administrative	38,827	24,275	67,652	49,633
Depreciation and amortization	20,819	15,528	36,130	31,486
Intercompany charges (income), net	0	0	0	0
Total	361,162	260,042	662,364	556,545
Interest expense, net	(5,748)	(4,177)	(9,946)	(8,350)
Other income, net	428	2,357	2,042	5,317
INCOME BEFORE INCOME TAXES	2,844	5,545	22,345	27,403
PROVISION (BENEFIT) FOR INCOME TAXES	1,381	2,060	9,022	10,952
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	1,463	3,485	13,323	16,451
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	1,463	3,485	13,323	16,451
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	11	(58)	13	(144)
COMPREHENSIVE INCOME (LOSS)	1,474	3,427	13,336	16,307
Parent
Revenues [Abstract]
Contract revenues	0	0	0	0
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	0	0	0	0
General and administrative	14,900	6,171	23,309	12,578
Depreciation and amortization	639	768	1,380	1,556
Intercompany charges (income), net	(17,380)	(7,701)	(27,306)	(15,666)
Total	(1,841)	(762)	(2,617)	(1,532)
Interest expense, net	(1,523)	(768)	(2,299)	(1,538)
Other income, net	(318)	6	(318)	6
INCOME BEFORE INCOME TAXES	0	0	0	0
PROVISION (BENEFIT) FOR INCOME TAXES	0	0	0	0
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
EQUITY IN EARNINGS OF SUBSIDIARIES	1,463	3,485	13,323	16,451
NET INCOME	1,463	3,485	13,323	16,451
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	11	(58)	13	(144)
COMPREHENSIVE INCOME (LOSS)	1,474	3,427	13,336	16,307
Issuer
Revenues [Abstract]
Contract revenues	0	0	0	0
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	0	0	0	0
General and administrative	148	148	295	295
Depreciation and amortization	0	0	0	0
Intercompany charges (income), net	0	0	0	0
Total	148	148	295	295
Interest expense, net	(4,224)	(3,413)	(7,644)	(6,827)
Other income, net	0	0	0	0
INCOME BEFORE INCOME TAXES	(4,372)	(3,561)	(7,939)	(7,122)
PROVISION (BENEFIT) FOR INCOME TAXES	(1,808)	(1,392)	(3,205)	(2,832)
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	(2,564)	(2,169)	(4,734)	(4,290)
EQUITY IN EARNINGS OF SUBSIDIARIES	4,027	5,654	18,057	20,741
NET INCOME	1,463	3,485	13,323	16,451
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	11	(58)	13	(144)
COMPREHENSIVE INCOME (LOSS)	1,474	3,427	13,336	16,307
Subsidiary Guarantors
Revenues [Abstract]
Contract revenues	366,797	264,275	685,822	578,092
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	299,106	217,730	552,650	468,623
General and administrative	21,279	15,429	38,895	31,832
Depreciation and amortization	18,969	13,692	32,255	27,552
Intercompany charges (income), net	17,718	7,548	27,990	15,044
Total	357,072	254,399	651,790	543,051
Interest expense, net	(1)	4	(3)	15
Other income, net	756	2,352	2,321	5,413
INCOME BEFORE INCOME TAXES	10,480	12,232	36,350	40,469
PROVISION (BENEFIT) FOR INCOME TAXES	4,540	4,675	14,676	16,151
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	5,940	7,557	21,674	24,318
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	5,940	7,557	21,674	24,318
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0	0	0	0
COMPREHENSIVE INCOME (LOSS)	5,940	7,557	21,674	24,318
Non-Guarantor Subsidiaries
Revenues [Abstract]
Contract revenues	2,529	3,132	6,791	8,889
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	2,410	2,509	5,932	6,803
General and administrative	2,500	2,527	5,153	4,928
Depreciation and amortization	1,211	1,068	2,495	2,390
Intercompany charges (income), net	(338)	153	(684)	622
Total	5,783	6,257	12,896	14,743
Interest expense, net	0	0	0	0
Other income, net	(10)	(1)	39	(102)
INCOME BEFORE INCOME TAXES	(3,264)	(3,126)	(6,066)	(5,956)
PROVISION (BENEFIT) FOR INCOME TAXES	(1,351)	(1,223)	(2,449)	(2,367)
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	(1,913)	(1,903)	(3,617)	(3,589)
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	(1,913)	(1,903)	(3,617)	(3,589)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	11	(58)	13	(144)
COMPREHENSIVE INCOME (LOSS)	(1,902)	(1,961)	(3,604)	(3,733)
Eliminations and Reclassifications
Revenues [Abstract]
Contract revenues	0	0	0	0
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	0	0	0	0
General and administrative	0	0	0	0
Depreciation and amortization	0	0	0	(12)
Intercompany charges (income), net	0	0	0	0
Total	0	0	0	(12)
Interest expense, net	0	0	0	0
Other income, net	0	0	0	0
INCOME BEFORE INCOME TAXES	0	0	0	12
PROVISION (BENEFIT) FOR INCOME TAXES	0	0	0	0
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	12
EQUITY IN EARNINGS OF SUBSIDIARIES	(5,490)	(9,139)	(31,380)	(37,192)
NET INCOME	(5,490)	(9,139)	(31,380)	(37,180)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(22)	116	(26)	288
COMPREHENSIVE INCOME (LOSS)	$ (5,512)	$ (9,023)	$ (31,406)	$ (36,892)