Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Jul. 31, 2015	Jul. 25, 2014	Apr. 24, 2015	Apr. 25, 2014
Income Tax Contingency [Line Items]
Gross unrecognized tax benefits	$ 243	$ 277	$ 272	$ 236
Unrecognized tax benefits included in other long-term liabilities	193
Unrecognized tax benefits that would affect provision for income taxes	148
Estimated potential decrease in unrecognized tax benefit balance	47
Federal Income Tax
Income Tax Contingency [Line Items]
Resolution of income tax examinations	13	$ 47
Federal Income Tax | Maximum
Income Tax Contingency [Line Items]
Expected additional tax expense	$ 10