Investments (Detail) (USD $) In Millions, unless otherwise specified	Aug. 02, 2014	Aug. 03, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 22.5		[1]
Fair Value	22.3		[1]
US Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Cost	10.0		[1]
Fair Value	9.9		[1]
US government agency securities
Schedule of Available-for-sale Securities [Line Items]
Cost	1.3		[1]
Fair Value	1.3		[1]
Corporate bonds and notes
Schedule of Available-for-sale Securities [Line Items]
Cost	8.7		[1]
Fair Value	8.6		[1]
Corporate equity securities
Schedule of Available-for-sale Securities [Line Items]
Cost	2.5		[1]
Fair Value	$ 2.5		[1]

[1] n/a Not applicable as all investments were acquired as part of the Acquisition that occurred during Fiscal 2015.