Financial Instruments - Investments by Category and Related Balance Sheet Classification (Details) - USD ($) $ in Millions	Jan. 24, 2020	Apr. 26, 2019
Schedule of Investments [Line Items]
Cost	$ 7,893	$ 5,540
Unrealized Gains	85	20
Unrealized Losses	(26)	(61)
Fair Value	7,952	5,499
Investments
Schedule of Investments [Line Items]
Fair Value	7,919	5,455
Other Assets
Schedule of Investments [Line Items]
Fair Value	33	44
Level 2
Schedule of Investments [Line Items]
Cost	7,234	4,964
Unrealized Gains	68	19
Unrealized Losses	(23)	(51)
Fair Value	7,279	4,932
Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	7,279	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	5,155	3,500
Unrealized Gains	52	14
Unrealized Losses	(8)	(21)
Fair Value	5,199	3,493
Corporate debt securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	5,199	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	623	529
Unrealized Gains	17	1
Unrealized Losses	0	(7)
Fair Value	640	523
U.S. government and agency securities | Level 1 | Investments
Schedule of Investments [Line Items]
Fair Value	640	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	900	387
Unrealized Gains	0	1
Unrealized Losses	0	(7)
Fair Value	900	381
U.S. government and agency securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	900	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	655	537
Unrealized Gains	13	3
Unrealized Losses	(13)	(20)
Fair Value	655	520
Mortgage-backed securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	655	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	13	11
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	13	11
Non-U.S. government and agency securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	13	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	511	529
Unrealized Gains	3	1
Unrealized Losses	(2)	(3)
Fair Value	512	527
Other asset-backed securities | Level 2 | Investments
Schedule of Investments [Line Items]
Fair Value	512	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	36	47
Unrealized Gains	0	0
Unrealized Losses	(3)	(3)
Fair Value	33	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	$ 33	$ 44