Available-for-Sale Debt and Equity Investments - Available-for-Sale Investments With Gross Unrealized Losses (Details) - USD ($) $ in Millions	Jan. 23, 2021	Jul. 25, 2020
Debt Securities, Available-for-sale [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	$ 1,521	$ 1,358
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	(4)	(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	1,521	1,361
TOTAL, Gross Unrealized Losses	(4)	(7)
U.S. government securities
Debt Securities, Available-for-sale [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	109
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	109
TOTAL, Gross Unrealized Losses	0
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	36	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	36	33
TOTAL, Gross Unrealized Losses	0	0
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	663	1,060
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	(1)	(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	663	1,063
TOTAL, Gross Unrealized Losses	(1)	(6)
U.S. agency mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	698	265
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	(3)	(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	698	265
TOTAL, Gross Unrealized Losses	(3)	$ (1)
Certificates of deposit
Debt Securities, Available-for-sale [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