Available-for-Sale Debt Investments and Equity Investments (Available-for-Sale Investments With Gross Unrealized Losses) (Details) - USD ($) $ in Millions	Apr. 27, 2019	Jul. 28, 2018
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	$ 1,907	$ 21,093
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	(7)	(391)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	15,489	9,019
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	(141)	(156)
TOTAL, Fair Value	17,396	30,112
TOTAL, Gross Unrealized Losses	(148)	(547)
U.S. government securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	8	2,966
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	0	(20)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	1,409	4,303
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	(4)	(23)
TOTAL, Fair Value	1,417	7,269
TOTAL, Gross Unrealized Losses	(4)	(43)
U.S. government agency securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	0	206
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	0	(2)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	263	521
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	(1)	(3)
TOTAL, Fair Value	263	727
TOTAL, Gross Unrealized Losses	(1)	(5)
Non-U.S. government and agency securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value		105
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses		(1)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value		103
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses		0
TOTAL, Fair Value		208
TOTAL, Gross Unrealized Losses		(1)
Corporate debt securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	1,851	16,990
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	(7)	(344)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	12,662	3,511
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	(108)	(101)
TOTAL, Fair Value	14,513	20,501
TOTAL, Gross Unrealized Losses	(115)	(445)
U.S. agency mortgage-backed securities
Schedule of Investments [Line Items]
UNREALIZED LOSSES LESS THAN 12 MONTHS, Fair Value	48	826
UNREALIZED LOSSES LESS THAN 12 MONTHS, Gross Unrealized Losses	0	(24)
UNREALIZED LOSSES 12 MONTHS OR GREATER, Fair Value	1,155	581
UNREALIZED LOSSES 12 MONTHS OR GREATER, Gross Unrealized Losses	(28)	(29)
TOTAL, Fair Value	1,203	1,407
TOTAL, Gross Unrealized Losses	$ (28)	$ (53)