Available-for-Sale Debt and Equity Investments - Available-for-Sale Investments With Gross Unrealized Losses (Details) - USD ($) $ in Millions	Oct. 24, 2020	Jul. 25, 2020
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	$ 2,308	$ 1,358
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	(8)	(7)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	0	3
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	0	0
TOTAL, Fair Value	2,308	1,361
TOTAL, Gross Unrealized Losses	(8)	(7)
U.S. government securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	144
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	0
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	0
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	0
TOTAL, Fair Value	144
TOTAL, Gross Unrealized Losses	0
U.S. government agency securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	65	33
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	0	0
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	0	0
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	0	0
TOTAL, Fair Value	65	33
TOTAL, Gross Unrealized Losses	0	0
Corporate debt securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	1,008	1,060
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	(2)	(6)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	0	3
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	0	0
TOTAL, Fair Value	1,008	1,063
TOTAL, Gross Unrealized Losses	(2)	(6)
U.S. agency mortgage-backed securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	1,076	265
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	(6)	(1)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	0	0
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	0	0
TOTAL, Fair Value	1,076	265
TOTAL, Gross Unrealized Losses	(6)	$ (1)
Certificates of deposit
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	15
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	0
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	0
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	0
TOTAL, Fair Value	15
TOTAL, Gross Unrealized Losses	$ 0