Financial Instruments - Investments by Category and Related Balance Sheet Classification (Details) - USD ($) $ in Millions	Jul. 26, 2019	Apr. 26, 2019
Schedule of Investments [Line Items]
Cost	$ 5,633	$ 5,540
Unrealized Gains	49	20
Unrealized Losses	(35)	(61)
Fair Value	5,647	5,499
Investments
Schedule of Investments [Line Items]
Fair Value	5,603	5,455
Other Assets
Schedule of Investments [Line Items]
Fair Value	44	44
Level 2
Schedule of Investments [Line Items]
Cost	5,037	4,964
Unrealized Gains	41	19
Unrealized Losses	(32)	(51)
Fair Value	5,046	4,932
Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	5,046	4,932
Level 2 | Other Assets
Schedule of Investments [Line Items]
Fair Value	0	0
Corporate debt securities | Level 2
Schedule of Investments [Line Items]
Cost	3,123	3,500
Unrealized Gains	30	14
Unrealized Losses	(13)	(21)
Fair Value	3,140	3,493
Corporate debt securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	3,140	3,493
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	549	529
Unrealized Gains	8	1
Unrealized Losses	0	(7)
Fair Value	557	523
U.S. government and agency securities | Level 1 | Investments
Schedule of Investments [Line Items]
Fair Value	557	523
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	788	387
Unrealized Gains	0	1
Unrealized Losses	(2)	(7)
Fair Value	786	381
U.S. government and agency securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	786	381
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	578	537
Unrealized Gains	8	3
Unrealized Losses	(14)	(20)
Fair Value	572	520
Mortgage-backed securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	572	520
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	11	11
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	11	11
Non-U.S. government and agency securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	11	11
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	537	529
Unrealized Gains	3	1
Unrealized Losses	(3)	(3)
Fair Value	537	527
Other asset-backed securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	537	527
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	47	47
Unrealized Gains	0	0
Unrealized Losses	(3)	(3)
Fair Value	44	44
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	$ 44	$ 44