Supplementary Balance Sheet Information (Narrative) (Details) (USD $)	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Balance Sheet Related Disclosures [Abstract]
Depreciation expense	$ 130,200,000	$ 124,500,000	$ 116,300,000
Amortization expense for intangible assets	2,500,000	3,100,000	1,700,000
Estimated amortization expense for intangible assets, year one	3,330,000
Estimated amortization expense for intangible assets, year two	3,300,000
Estimated amortization expense for intangible assets, year three	3,300,000
Estimated amortization expense for intangible assets, year four	3,300,000
Estimated amortization expense for intangible assets, year five	$ 3,300,000