Property and Equipment, Net (Details) (USD $)	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 892,717,000	$ 833,068,000
Less accumulated depreciation and amortization	(292,329,000)	(259,554,000)
Property, Plant and Equipment, Net, Total	600,388,000	573,514,000
Depreciation Expense	40,200,000	39,000,000	37,300,000
Amortization expense of software	800,000	300,000	400,000
Transportation and Other Equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	65,009,000	61,245,000
Office Furniture and Equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	53,411,000	43,307,000
Software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	46,761,000	22,915,000
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	343,170,000	306,251,000
Buildings and Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 384,366,000	$ 399,350,000