Stockholders' Equity - Schedule of Employee Stock Purchase Plan (ESPP) (Detail) - USD ($) shares in Millions, $ in Millions	6 Months Ended
Oct. 26, 2018	Oct. 27, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under the ESPP	2	2
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of shares	$ 49	$ 42

Number of shares issued during the period as a result of an employee stock purchase plan.

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Name:	us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration