Summary of Significant Accounting Policies Inventories (Details) - USD ($) $ in Thousands	12 Months Ended
Jul. 31, 2018	Jul. 31, 2017
Inventory Disclosure [Abstract]
Percentage of LIFO Inventory	15.00%	13.50%
Inventory, LIFO Reserve, Effect on Income, Net	$ 7,015	$ 6,807

The difference between the change in the inventory reserve representing the cumulative difference in cost between the first in, first out and the last in, first out inventory valuation methods and any LIFO decrement which have been reflected in the statement of income during the period.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration