Derivative Instruments (Additional Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jan. 24, 2015	Jan. 24, 2015	Jul. 26, 2014
Derivative [Line Items]
Net derivative gains to be reclassified from AOCI into earnings in next twelve months	$ 102.0
Net liability position	162	162	67
Long-term Debt
Derivative [Line Items]
Description of Interest Rate Derivative Activities		In fiscal 2014 and 2013, the Company entered into interest rate swaps designated as fair value hedges related to fixed-rate senior notes that are due on various dates from 2017 through 2024. In the periods prior to fiscal 2013, the Company entered into interest rate swaps designated as fair value hedges related to fixed-rate senior notes that are due in 2016 and 2017.
Derivatives designated as cash flow hedging instruments:
Derivative [Line Items]
Foreign currency cash flow hedges maturity period, maximum, months	18 months
Net investment hedging instruments
Derivative [Line Items]
Foreign currency cash flow hedges maturity period, maximum, months	6 months
Fixed Income Securities [Member]
Derivative [Line Items]
Number of Interest Rate Derivatives Held	0	0	0
Right to request collateral subject to specified credit rating and in net liability position [Member]
Derivative [Line Items]
Net liability position	$ 0	0	$ 3