Financial Instruments - Investments by Category and Related Balance Sheet Classification (Details) - USD ($) $ in Millions	Jul. 31, 2020	Apr. 24, 2020
Schedule of Investments [Line Items]
Cost	$ 6,399	$ 6,847
Unrealized Gains	221	135
Unrealized Losses	(72)	(141)
Fair Value	6,548	6,841
Investments
Schedule of Investments [Line Items]
Fair Value	6,513	6,808
Other Assets
Schedule of Investments [Line Items]
Fair Value	35	33
Level 2
Schedule of Investments [Line Items]
Cost	5,845	6,269
Unrealized Gains	175	88
Unrealized Losses	(71)	(138)
Fair Value	5,949	6,219
Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	5,949	6,219
Level 2 | Other Assets
Schedule of Investments [Line Items]
Fair Value	0	0
Corporate debt securities | Level 2
Schedule of Investments [Line Items]
Cost	3,859	4,285
Unrealized Gains	139	66
Unrealized Losses	(39)	(90)
Fair Value	3,959	4,261
Corporate debt securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	3,959	4,261
Corporate debt securities | Level 2 | Other Assets
Schedule of Investments [Line Items]
Fair Value	0	0
U.S. government and agency securities | Level 1
Schedule of Investments [Line Items]
Cost	518	542
Unrealized Gains	46	47
Unrealized Losses	0	0
Fair Value	564	589
U.S. government and agency securities | Level 1 | Investments
Schedule of Investments [Line Items]
Fair Value	564	589
U.S. government and agency securities | Level 1 | Other Assets
Schedule of Investments [Line Items]
Fair Value	0	0
U.S. government and agency securities | Level 2
Schedule of Investments [Line Items]
Cost	779	746
Unrealized Gains	2	1
Unrealized Losses	0	0
Fair Value	781	747
U.S. government and agency securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	781	747
U.S. government and agency securities | Level 2 | Other Assets
Schedule of Investments [Line Items]
Fair Value	0	0
Mortgage-backed securities | Level 2
Schedule of Investments [Line Items]
Cost	669	705
Unrealized Gains	28	20
Unrealized Losses	(22)	(28)
Fair Value	675	697
Mortgage-backed securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	675	697
Mortgage-backed securities | Level 2 | Other Assets
Schedule of Investments [Line Items]
Fair Value	0	0
Non-U.S. government and agency securities | Level 2
Schedule of Investments [Line Items]
Cost	36	34
Unrealized Gains	2	0
Unrealized Losses	0	0
Fair Value	38	34
Non-U.S. government and agency securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	38	34
Non-U.S. government and agency securities | Level 2 | Other Assets
Schedule of Investments [Line Items]
Fair Value	0	0
Other asset-backed securities | Level 2
Schedule of Investments [Line Items]
Cost	502	499
Unrealized Gains	4	1
Unrealized Losses	(10)	(20)
Fair Value	496	480
Other asset-backed securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	496	480
Other asset-backed securities | Level 2 | Other Assets
Schedule of Investments [Line Items]
Fair Value	0	0
Auction rate securities | Level 3
Schedule of Investments [Line Items]
Cost	36	36
Unrealized Gains	0	0
Unrealized Losses	(1)	(3)
Fair Value	35	33
Auction rate securities | Level 3 | Investments
Schedule of Investments [Line Items]
Fair Value	0	0
Auction rate securities | Level 3 | Other Assets
Schedule of Investments [Line Items]
Fair Value	$ 35	$ 33