Income Taxes - Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	9 Months Ended
Jan. 27, 2017	Jan. 29, 2016
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 216	$ 272
Additions based on tax positions related to the current year	5	13
Additions for tax positions of prior years	6	21
Decreases for tax positions of prior years	0	(38)
Settlements	(12)	(52)
Balance at end of period	$ 215	$ 216

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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