v3.19.1

Fair Value (Fair Value, Nonrecurring Measurement) (Details) - Fair Value, Measurements, Nonrecurring - Level 3 - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Apr. 27, 2019 | Apr. 28, 2018 | Apr. 27, 2019 | Apr. 28, 2018
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items] |  |  |  |
Total gains (losses) for nonrecurring measurements | $ (3) | $ (18) | $ 3 | $ (37)
Non-marketable equity securities and equity method investments |  |  |  |
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items] |  |  |  |
Total gains (losses) for nonrecurring measurements | (3) | (17) | 3 | (56)
Purchased intangible assets (impaired) |  |  |  |
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items] |  |  |  |
Total gains (losses) for nonrecurring measurements | 0 | (1) | 0 | (1)
Property held for sale—land and buildings |  |  |  |
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items] |  |  |  |
Total gains (losses) for nonrecurring measurements | $ 0 | $ 0 | $ 0 | $ 20

X
- Definition Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items] + References No definition available. + Details
Name: | csco_FairValueAssetsAndLiabilitiesMeasuredOnNonrecurringBasisLineItems
Namespace Prefix: | csco_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of addition (reduction) to the amount at which an asset could be incurred (settled) in a current transaction between willing parties. + References No definition available. + Details
Name: | us-gaap_AssetsFairValueAdjustment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_FiniteLivedIntangibleAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=csco_PropertyHeldforSaleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |