Supplementary Balance Sheet Information (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Asset impairments	$ 28,372	$ 0	$ 0
Finite-Lived Intangible Asset, Expected Amortization, Year Two	4,326
Finite-Lived Intangible Asset, Expected Amortization, Year Five	4,326
Finite-Lived Intangible Asset, Expected Amortization, Year Four	4,326
Finite-Lived Intangible Asset, Expected Amortization, Year Three	4,326
Depreciation expense	243,100	210,700	199,200
Amortization of Intangible Assets	$ 6,500	$ 7,400	$ 5,300

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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