Accounts Receivable II (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 26, 2013	Jan. 28, 2012	Jan. 26, 2013	Jan. 28, 2012
Receivables [Roll Forward]
Allowance for doubtful accounts at beginning of period	$ 278	$ 376	$ 270	$ 368
Bad debt expense (recovery), net	23	32	32	68
Amounts charged against the allowance	(22)	1	(23)	(27)
Allowance for doubtful accounts at end of period	$ 279	$ 409	$ 279	$ 409