Comprehensive Income (Loss) - AOCI components (Details) - USD ($) $ in Millions	12 Months Ended
Jul. 27, 2019	Jul. 28, 2018	Jul. 29, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	$ 43,204
Other comprehensive income (loss)	225	$ (940)	$ 373
Effect of adoption of accounting standards	3,729	9
Balance, end of period	33,571	43,204
Net Unrealized Gains (Losses) on Available-for-Sale Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(310)	373	413
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	560	(543)	(164)
(Gains) losses reclassified out of AOCI	13	(287)	87
Tax benefit (expense)	(95)	93	37
Other comprehensive income (loss)	478	(737)	(40)
Effect of adoption of accounting standards	(168)	54
Balance, end of period	0	(310)	373
Net Unrealized Gains (Losses) Cash Flow Hedging Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(11)	32	(59)
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	0	21	22
(Gains) losses reclassified out of AOCI	(3)	(68)	79
Tax benefit (expense)	0	4	(10)
Other comprehensive income (loss)	(3)	(43)	91
Effect of adoption of accounting standards	0	0
Balance, end of period	(14)	(11)	32
Cumulative Translation Adjustment and Actuarial Gains and Losses
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(528)	(359)	(680)
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	(267)	(159)	318
(Gains) losses reclassified out of AOCI	2	7	16
Tax benefit (expense)	15	(8)	(13)
Other comprehensive income (loss)	(250)	(160)	321
Effect of adoption of accounting standards	0	(9)
Balance, end of period	(778)	(528)	(359)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, beginning of period	(849)	46	(326)
Other comprehensive income (loss) before reclassifications attributable to Cisco Systems, Inc.	293	(681)	176
(Gains) losses reclassified out of AOCI	12	(348)	182
Tax benefit (expense)	(80)	89	14
Other comprehensive income (loss)	225	(940)	372
Effect of adoption of accounting standards	(168)	45
Balance, end of period	$ (792)	$ (849)	$ 46

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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