CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended
Oct. 27, 2018	Oct. 28, 2017
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Tax of amortization of pension actuarial loss	$ (43)	$ (58)

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e640-108580

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration