Supplementary Balance Sheet Information (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Balance Sheet Related Disclosures [Abstract]
Depreciation expense	$ 124.5	$ 116.3	$ 109.8
Amortization expense for intangible assets	3.1	1.7	0.8
Estimated amortization expense for intangible assets, year one	1.1
Estimated amortization expense for intangible assets, year two	1.1
Estimated amortization expense for intangible assets, year three	1.1
Estimated amortization expense for intangible assets, year four	1.1
Estimated amortization expense for intangible assets, year five	$ 1.1