Supplementary Balance Sheet Information (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Balance Sheet Related Disclosures [Abstract]
Depreciation expense	$ 156,800	$ 144,000	$ 136,600
Amortization of Intangible Assets	4,700	$ 5,100	$ 4,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	2,400
Estimated amortization expense for intangible assets, year two	2,400
Estimated amortization expense for intangible assets, year three	2,400
Estimated amortization expense for intangible assets, year four	2,400
Estimated amortization expense for intangible assets, year five	$ 2,400