Supplemental Consolidating Financial Statements Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 27, 2013	Apr. 28, 2012	Apr. 27, 2013	Apr. 28, 2012
Revenues [Abstract]
Contract revenues	$ 437,367	$ 296,103	$ 1,129,980	$ 883,085
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	357,664	241,386	916,247	716,812
General and administrative	38,205	26,956	105,857	76,589
Depreciation and amortization	24,531	15,561	60,660	47,047
Intercompany charges (income), net	0	0	0	0
Total	420,400	283,903	1,082,764	840,448
Interest expense, net	(6,637)	(4,178)	(16,582)	(12,528)
Other income, net	1,477	7,627	3,519	12,943
INCOME BEFORE INCOME TAXES	11,807	15,649	34,153	43,052
PROVISION (BENEFIT) FOR INCOME TAXES	4,608	6,004	13,631	16,956
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	7,199	9,645	20,522	26,096
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	7,199	9,645	20,522	26,096
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(21)	90	(8)	(54)
COMPREHENSIVE INCOME (LOSS)	7,178	9,735	20,514	26,042
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	10,195	7,476	33,504	20,054
Depreciation and amortization	754	792	2,134	2,347
Intercompany charges (income), net	(12,592)	(9,016)	(39,897)	(24,682)
Total	(1,643)	(748)	(4,259)	(2,281)
Interest expense, net	(1,643)	(764)	(3,941)	(2,303)
Other income, net	0	16	(318)	22
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	7,199	9,645	20,522	26,096
NET INCOME	7,199	9,645	20,522	26,096
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(21)	90	(8)	(54)
COMPREHENSIVE INCOME (LOSS)	7,178	9,735	20,514	26,042
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	147	128	442	423
Depreciation and amortization	0	0	0	0
Intercompany charges (income), net	0	0	0	0
Total	147	128	442	423
Interest expense, net	(4,963)	(3,416)	(12,607)	(10,243)
Other income, net	0	0	0	0
INCOME BEFORE INCOME TAXES	(5,110)	(3,544)	(13,049)	(10,666)
PROVISION (BENEFIT) FOR INCOME TAXES	(2,002)	(1,349)	(5,208)	(4,181)
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	(3,108)	(2,195)	(7,841)	(6,485)
EQUITY IN EARNINGS OF SUBSIDIARIES	10,307	11,840	28,363	32,581
NET INCOME	7,199	9,645	20,522	26,096
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(21)	90	(8)	(54)
COMPREHENSIVE INCOME (LOSS)	7,178	9,735	20,514	26,042
Subsidiary Guarantors
Revenues [Abstract]
Contract revenues	434,595	293,521	1,120,417	871,613
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	355,231	239,251	907,881	707,874
General and administrative	24,597	16,899	63,492	48,731
Depreciation and amortization	22,538	13,637	54,793	41,190
Intercompany charges (income), net	12,981	8,906	40,971	23,950
Total	415,347	278,693	1,067,137	821,745
Interest expense, net	(31)	2	(34)	18
Other income, net	1,489	7,001	3,810	12,415
INCOME BEFORE INCOME TAXES	20,706	21,831	57,056	62,301
PROVISION (BENEFIT) FOR INCOME TAXES	8,095	8,350	22,772	24,500
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	12,611	13,481	34,284	37,801
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	12,611	13,481	34,284	37,801
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0	0	0	0
COMPREHENSIVE INCOME (LOSS)	12,611	13,481	34,284	37,801
Non-Guarantor Subsidiaries
Revenues [Abstract]
Contract revenues	2,772	2,582	9,563	11,472
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	2,433	2,135	8,366	8,938
General and administrative	3,266	2,453	8,419	7,381
Depreciation and amortization	1,239	1,132	3,733	3,522
Intercompany charges (income), net	(389)	110	(1,074)	732
Total	6,549	5,830	19,444	20,573
Interest expense, net	0	0	0	0
Other income, net	(12)	610	27	506
INCOME BEFORE INCOME TAXES	(3,789)	(2,638)	(9,854)	(8,595)
PROVISION (BENEFIT) FOR INCOME TAXES	(1,485)	(997)	(3,933)	(3,363)
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	(2,304)	(1,641)	(5,921)	(5,232)
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	(2,304)	(1,641)	(5,921)	(5,232)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(21)	90	(8)	(54)
COMPREHENSIVE INCOME (LOSS)	(2,325)	(1,551)	(5,929)	(5,286)
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	(17,506)	(21,485)	(48,885)	(58,677)
NET INCOME	(17,506)	(21,485)	(48,885)	(58,665)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	42	(180)	16	108
COMPREHENSIVE INCOME (LOSS)	$ (17,464)	$ (21,665)	$ (48,869)	$ (58,557)