Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Name:	us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Oct. 27, 2018	Jul. 31, 2018	Oct. 28, 2017	Jul. 31, 2017
Cash, Cash Equivalents and Restricted Cash [Abstract]
Cash and cash equivalents	$ 12,628	$ 13,496
Restricted cash included in other assets	247	250
Total cash, cash equivalents and restricted cash	12,875	13,746	$ 15,950	$ 13,135
Money Market Funds [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Short-term investments	$ 600	$ 400