Comprehensive Income (AOCI components) (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 29, 2017	Jul. 30, 2016	Jul. 25, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	$ 63,586
Balance, end of period	66,137	$ 63,586
Net Unrealized Gains (Losses) on Available-for-Sale Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	413	310	$ 424
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	(164)	151	(28)
(Gains) losses reclassified out of AOCI	87	1	(157)
Tax benefit (expense)	37	(49)	71
Balance, end of period	373	413	310
Net Unrealized Gains (Losses) Cash Flow Hedging Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(59)	(16)	(12)
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	22	(66)	(159)
(Gains) losses reclassified out of AOCI	79	20	154
Tax benefit (expense)	(10)	3	1
Balance, end of period	32	(59)	(16)
Cumulative Translation Adjustment and Actuarial Gains and Losses
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(680)	(233)	265
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	318	(399)	(563)
(Gains) losses reclassified out of AOCI	16	(6)	2
Tax benefit (expense)	(13)	(42)	63
Balance, end of period	(359)	(680)	(233)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(326)	61	677
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	176	(314)	(750)
(Gains) losses reclassified out of AOCI	182	15	(1)
Tax benefit (expense)	14	(88)	135
Balance, end of period	$ 46	$ (326)	$ 61