Financial Instruments and Fair Value - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis by Balance Sheet Grouping (Detail) (USD $) In Millions, unless otherwise specified	Jul. 27, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	$ 685.9
Short-term investments	3,911.7
Other current assets	15.1
Other non-current assets	66.5
Total	4,679.2
Other current liabilities	0.4
Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	481.9
Short-term investments	224.9
Other current assets	6.2
Other non-current assets	20.2
Total	733.2
Other current liabilities	0
Fair Value, Inputs, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	204.0
Short-term investments	3,686.8
Other current assets	8.9
Other non-current assets	0
Total	3,899.7
Other current liabilities	0.4
Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0
Short-term investments	0
Other current assets	0
Other non-current assets	46.3
Total	46.3
Other current liabilities	$ 0