Financial Instruments - Activity Related to the Company's Investment Portfolio and Available-for-sale Debt Securities Contractual Maturities (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Oct. 26, 2018	Oct. 27, 2017	Oct. 26, 2018	Oct. 27, 2017	Apr. 27, 2018
Activities Related to Investment Portfolio
Proceeds from sales	$ 804	$ 980	$ 1,916	$ 1,951
Gross realized gains	2	11	8	19
Gross realized losses	(12)	$ (11)	(19)	$ (14)
AFS Debt Maturities
Due in one year or less	1,103		1,103
Due after one year through five years	2,568		2,568
Due after five years through ten years	2,479		2,479
Due after ten years	116		116
Fair Value	$ 6,266		$ 6,266		$ 6,820

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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