Stock-Based Awards (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 24, 2015	Jul. 25, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 21.1
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 2.6
Total compensation cost not yet recognized, period for recognition	2 years 5 months 1 day
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 7.1
Total compensation cost not yet recognized, period for recognition	2 years 7 months 1 day
Granted (in shares)	32,451
Shares outstanding (in shares)	351,856	322,008
Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 11.4
Total compensation cost not yet recognized, period for recognition	1 year 6 months 1 day
Compensation expense	$ 2.9
RSUs outstanding (in shares)	16,558
Granted (in shares)	33,116
Forfeited or cancelled (in shares)	169,790
Shares outstanding (in shares)	763,458	945,540
Target Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)	688,453
Supplemental Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	16,558
Shares outstanding (in shares)	75,005