Supplemental Consolidating Financial Statements - Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 25, 2014	Oct. 26, 2013
Revenues [Abstract]
Contract revenues	$ 510,389	$ 512,720
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	403,468	410,119
General and administrative	44,696	43,075
Depreciation and amortization	22,930	23,552
Intercompany charges (income), net	0	0
Interest income (expense), net	(6,749)	(6,886)
Other income, net	1,795	2,012
INCOME BEFORE INCOME TAXES	34,341	31,100
PROVISION (BENEFIT) FOR INCOME TAXES	13,534	12,440
Net income (loss) before equity in earnings of subsidiaries	20,807	18,660
EQUITY IN EARNINGS (LOSSES) OF SUBSIDIARIES	0	0
NET INCOME	20,807	18,660
Foreign currency translation loss, net of tax	(268)	(60)
COMPREHENSIVE INCOME (LOSS)	20,539	18,600
Parent
Revenues [Abstract]
Contract revenues	0	0
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	0	0
General and administrative	12,833	11,237
Depreciation and amortization	1,239	854
Intercompany charges (income), net	(15,822)	(13,976)
Interest income (expense), net	(1,750)	(1,888)
Other income, net	0	3
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 (LOSSES) OF SUBSIDIARIES	20,807	18,660
NET INCOME	20,807	18,660
Foreign currency translation loss, net of tax	(268)	(60)
COMPREHENSIVE INCOME (LOSS)	20,539	18,600
Issuer
Revenues [Abstract]
Contract revenues	0	0
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	0	0
General and administrative	100	226
Depreciation and amortization	0	0
Intercompany charges (income), net	0	0
Interest income (expense), net	(4,999)	(4,994)
Other income, net	0	0
INCOME BEFORE INCOME TAXES	(5,099)	(5,220)
PROVISION (BENEFIT) FOR INCOME TAXES	(2,010)	(2,087)
Net income (loss) before equity in earnings of subsidiaries	(3,089)	(3,133)
EQUITY IN EARNINGS (LOSSES) OF SUBSIDIARIES	23,896	21,793
NET INCOME	20,807	18,660
Foreign currency translation loss, net of tax	(268)	(60)
COMPREHENSIVE INCOME (LOSS)	20,539	18,600
Subsidiary Guarantors
Revenues [Abstract]
Contract revenues	505,689	509,430
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	400,091	407,695
General and administrative	28,168	28,945
Depreciation and amortization	20,581	21,621
Intercompany charges (income), net	16,408	14,110
Interest income (expense), net	0	(4)
Other income, net	1,779	1,945
INCOME BEFORE INCOME TAXES	42,220	39,000
PROVISION (BENEFIT) FOR INCOME TAXES	16,640	15,600
Net income (loss) before equity in earnings of subsidiaries	25,580	23,400
EQUITY IN EARNINGS (LOSSES) OF SUBSIDIARIES	(139)	0
NET INCOME	25,441	23,400
Foreign currency translation loss, net of tax	0	0
COMPREHENSIVE INCOME (LOSS)	25,441	23,400
Non-Guarantor Subsidiaries
Revenues [Abstract]
Contract revenues	4,700	3,290
EXPENSES:
Costs of earned revenues, excluding depreciation and amortization	3,377	2,424
General and administrative	3,595	2,667
Depreciation and amortization	1,110	1,077
Intercompany charges (income), net	(586)	(134)
Interest income (expense), net	0	0
Other income, net	16	64
INCOME BEFORE INCOME TAXES	(2,780)	(2,680)
PROVISION (BENEFIT) FOR INCOME TAXES	(1,096)	(1,073)
Net income (loss) before equity in earnings of subsidiaries	(1,684)	(1,607)
EQUITY IN EARNINGS (LOSSES) OF SUBSIDIARIES	0	0
NET INCOME	(1,684)	(1,607)
Foreign currency translation loss, net of tax	(268)	(60)
COMPREHENSIVE INCOME (LOSS)	(1,952)	(1,667)
Eliminations and Reclassifications
Revenues [Abstract]
Contract revenues	0	0
EXPENSES:
Costs 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
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 (LOSSES) OF SUBSIDIARIES	(44,564)	(40,453)
NET INCOME	(44,564)	(40,453)
Foreign currency translation loss, net of tax	536	120
COMPREHENSIVE INCOME (LOSS)	$ (44,028)	$ (40,333)