Supplemental Consolidating Financial Statements - Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 26, 2014	Apr. 27, 2013	Apr. 26, 2014	Apr. 27, 2013
Revenues [Abstract]
Contract revenues	$ 426,284	$ 437,367	$ 1,329,522	$ 1,129,980
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	350,352	357,664	1,087,824	916,247
General and administrative	39,162	38,205	120,799	105,857
Depreciation and amortization	22,726	24,531	69,713	60,660
Intercompany charges (income), net	0	0	0	0
Total	412,240	420,400	1,278,336	1,082,764
Interest income (expense), net	(6,563)	(6,637)	(20,249)	(16,582)
Other income, net	5,593	1,477	8,200	3,519
INCOME BEFORE INCOME TAXES	13,074	11,807	39,137	34,153
PROVISION (BENEFIT) FOR INCOME TAXES	5,179	4,608	15,649	13,631
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	7,895	7,199	23,488	20,522
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	7,895	7,199	23,488	20,522
Foreign currency translation gain	(46)	(21)	(332)	(8)
COMPREHENSIVE INCOME (LOSS)	7,849	7,178	23,156	20,514
Parent
Revenues [Abstract]
Contract revenues	0	0	0	0
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	0	0	0	0
General and administrative	9,878	10,195	31,398	33,504
Depreciation and amortization	1,164	754	3,058	2,134
Intercompany charges (income), net	(12,608)	(12,592)	(39,713)	(39,897)
Interest income (expense), net	(1,566)	(1,643)	(5,260)	(3,941)
Other income, net	0	0	3	(318)
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	7,895	7,199	23,488	20,522
NET INCOME	7,895	7,199	23,488	20,522
Foreign currency translation gain	(46)	(21)	(332)	(8)
COMPREHENSIVE INCOME (LOSS)	7,849	7,178	23,156	20,514
Issuer
Revenues [Abstract]
Contract revenues	0	0	0	0
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	0	0	0	0
General and administrative	211	147	651	442
Depreciation and amortization	0	0	0	0
Intercompany charges (income), net	0	0	0	0
Interest income (expense), net	(4,997)	(4,963)	(14,985)	(12,607)
Other income, net	0	0	0	0
INCOME BEFORE INCOME TAXES	(5,208)	(5,110)	(15,636)	(13,049)
PROVISION (BENEFIT) FOR INCOME TAXES	(2,063)	(2,002)	(6,252)	(5,208)
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	(3,145)	(3,108)	(9,384)	(7,841)
EQUITY IN EARNINGS OF SUBSIDIARIES	11,040	10,307	32,872	28,363
NET INCOME	7,895	7,199	23,488	20,522
Foreign currency translation gain	(46)	(21)	(332)	(8)
COMPREHENSIVE INCOME (LOSS)	7,849	7,178	23,156	20,514
Subsidiary Guarantors
Revenues [Abstract]
Contract revenues	423,853	434,595	1,321,684	1,120,417
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	348,602	355,231	1,081,975	907,881
General and administrative	26,308	24,597	80,574	63,492
Depreciation and amortization	20,506	22,538	63,357	54,793
Intercompany charges (income), net	12,669	12,981	40,049	40,971
Interest income (expense), net	0	(31)	(4)	(34)
Other income, net	5,554	1,489	8,130	3,810
INCOME BEFORE INCOME TAXES	21,322	20,706	63,855	57,056
PROVISION (BENEFIT) FOR INCOME TAXES	8,447	8,095	25,533	22,772
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	12,875	12,611	38,322	34,284
EQUITY IN EARNINGS OF SUBSIDIARIES	70	0	70	0
NET INCOME	12,945	12,611	38,392	34,284
Foreign currency translation gain	0	0	0	0
COMPREHENSIVE INCOME (LOSS)	12,945	12,611	38,392	34,284
Non-Guarantor Subsidiaries
Revenues [Abstract]
Contract revenues	2,431	2,772	7,838	9,563
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	1,750	2,433	5,849	8,366
General and administrative	2,765	3,266	8,176	8,419
Depreciation and amortization	1,056	1,239	3,298	3,733
Intercompany charges (income), net	(61)	(389)	(336)	(1,074)
Interest income (expense), net	0	0	0	0
Other income, net	39	(12)	67	27
INCOME BEFORE INCOME TAXES	(3,040)	(3,789)	(9,082)	(9,854)
PROVISION (BENEFIT) FOR INCOME TAXES	(1,205)	(1,485)	(3,632)	(3,933)
NET INCOME (LOSS) BEFORE EQUITY IN EARNINGS OF SUBSIDIARIES	(1,835)	(2,304)	(5,450)	(5,921)
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	(1,835)	(2,304)	(5,450)	(5,921)
Foreign currency translation gain	(46)	(21)	(332)	(8)
COMPREHENSIVE INCOME (LOSS)	(1,881)	(2,325)	(5,782)	(5,929)
Eliminations and Reclassifications
Revenues [Abstract]
Contract revenues	0	0	0	0
EXPENSES:
Cost of earned revenues, excluding depreciation and amortization	0	0	0	0
General and administrative	0	0	0	0
Depreciation and amortization	0	0	0	0
Intercompany charges (income), net	0	0	0	0
Interest income (expense), net	0	0	0	0
Other income, net	0	0	0	0
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	(19,005)	(17,506)	(56,430)	(48,885)
NET INCOME	(19,005)	(17,506)	(56,430)	(48,885)
Foreign currency translation gain	92	42	664	16
COMPREHENSIVE INCOME (LOSS)	$ (18,913)	$ (17,464)	$ (55,766)	$ (48,869)