Derivatives and Foreign Exchange Risk Management, Credit Risk and Other Disclosures (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Oct. 24, 2014	Oct. 24, 2014	Oct. 25, 2013	Apr. 25, 2014
General Discussion of Derivatives
Currency exchange rate gains/(losses)	$ 14	$ 2	$ 3
Statement [Line Items]
Derivative Assets and Liabilities, Net, Collateral, Obligation to Return Cash	80	80		0
Derivative, Collateral, Obligation to Return Cash	80	80		0
Italy, Spain, Portugal and Greece
Statement [Line Items]
Accounts receivable net of allowance	601	601		628
GREECE
Statement [Line Items]
Deferred Revenue	18	18		15
Foreign Currency Exchange Rate Contracts
General Discussion of Derivatives
Derivative, Notional Amount	6,790	6,790		8,051
Statement [Line Items]
Derivative, Collateral, Obligation to Return Cash	$ 75	$ 75		$ 0