Stockholders' Equity - Activity Related to Stock Options (Detail) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Jan. 26, 2018 USD ($) $ / shares shares
Number of Shares
Beginning balance, Number of Shares | shares	4
Options exercised, Number of Shares | shares	(2)
Ending balance, Number of Shares | shares	2
Options Exercisable, Number of Shares | shares	1
Weighted-Average Exercise Price
Beginning balance, Weighted-Average Exercise Price | $ / shares	$ 35.76
Options exercised, Weighted-Average Exercise Price | $ / shares	36.44
Ending balance, Weighted-Average Exercise Price | $ / shares	33.24
Options Exercisable, Weighted-Average Exercise Price | $ / shares	$ 37.57
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Outstanding, Weighted-Average Remaining Contractual Term	3 years 4 months 6 days
Exercisable, Weighted-Average Remaining Contractual Term	2 years 7 months 13 days
Outstanding, Aggregate Intrinsic Value | $	$ 49
Exercisable, Aggregate Intrinsic Value | $	$ 34