Share-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation	$ 2,586	$ 3,003	$ 4,011	$ 4,955
Nonvested Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation	2,115	2,146	3,098	3,412
Performance-Based Market Stock Units ("MSU Grants") [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation	$ 471	$ 857	$ 913	$ 1,543