Comprehensive Income (AOCI components) (Details) - USD ($) $ in Millions	6 Months Ended
	Jan. 28, 2017	Jan. 23, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	$ 63,586
Balance, end of period	63,811
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
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	(559)	(515)
(Gains) losses reclassified out of AOCI	15	20
Tax benefit (expense)	148	198
Balance, end of period	17	13
Net Unrealized Gains (Losses) Cash Flow Hedging Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(59)	(16)
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	(48)	(24)
(Gains) losses reclassified out of AOCI	39	8
Tax benefit (expense)	1	2
Balance, end of period	(67)	(30)
Cumulative Translation Adjustment and Actuarial Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(680)	(233)
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	(69)	(524)
(Gains) losses reclassified out of AOCI	(1)	1
Tax benefit (expense)	(1)	(34)
Balance, end of period	(751)	(790)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(326)	61
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	(676)	(1,063)
(Gains) losses reclassified out of AOCI	53	29
Tax benefit (expense)	148	166
Balance, end of period	$ (801)	$ (807)