Financial Instruments , Items Measured at Fair Value on a Recurring Basis that Used Significant Unobservable Inputs (Level 3) (Details) - Fair Value, Measurements, Recurring - Level 3 - USD ($) $ in Millions	12 Months Ended
	Apr. 26, 2019	Apr. 27, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning balance	$ 44	$ 45
Settlements	0	(1)
Ending balance	44	44
Corporate debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning balance	0	1
Settlements	0	(1)
Ending balance	0	0
Auction rate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning balance	44	44
Settlements	0	0
Ending balance	$ 44	$ 44