Stockholders' Equity - Summary of Activities Related to Dividends on Common Stock (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Jul. 31, 2015	Jul. 25, 2014
Dividends, Common Stock [Abstract]
Dividends per share declared	$ 0.180	$ 0.165
Dividend payments	$ 54	$ 53
Additional Paid-in Capital
Dividends, Common Stock [Abstract]
Dividend payments	$ 54	0
Retained Earnings
Dividends, Common Stock [Abstract]
Dividend payments		$ 53

Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

Name:	us-gaap_PaymentsOfDividends
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration