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Fair Value Measurements (Details) (USD $)
In Millions, unless otherwise specified |
Dec. 31, 2014
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Dec. 31, 2013
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|---|---|---|
| Trading securities | $ 523us-gaap_TradingSecurities | $ 3,956us-gaap_TradingSecurities |
| Available-for-sale Securities | 132us-gaap_AvailableForSaleSecurities | 389us-gaap_AvailableForSaleSecurities |
| Interest rate swap agreements | 84us-gaap_InterestRateDerivativeAssetsAtFairValue | 110us-gaap_InterestRateDerivativeAssetsAtFairValue |
| Other [assets] | 71us-gaap_OtherAssetsFairValueDisclosure | 81us-gaap_OtherAssetsFairValueDisclosure |
| Fair Value, Assets Measured on Recurring Basis, Total | 810us-gaap_AssetsFairValueDisclosure | 4,536us-gaap_AssetsFairValueDisclosure |
| Derivative component of prepaid forward sale agreements and indexed debt instruments | 361cmcsa_DerivativeFairValueOfEmbeddedDerivativeLiabilityComponentOfPrepaidForwardSaleAgreementsAndIndexedDebtInstruments | 2,816cmcsa_DerivativeFairValueOfEmbeddedDerivativeLiabilityComponentOfPrepaidForwardSaleAgreementsAndIndexedDebtInstruments |
| Contractual Obligation | 883us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations | 747us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations |
| Contingent consideration | 644us-gaap_BusinessCombinationContingentConsiderationLiability | 684us-gaap_BusinessCombinationContingentConsiderationLiability |
| Other [liabilities] | 8us-gaap_OtherLiabilitiesFairValueDisclosure | 16us-gaap_OtherLiabilitiesFairValueDisclosure |
| Fair Value Liabilities Measured On Recurring Basis | 1,896us-gaap_LiabilitiesFairValueDisclosure | 4,263us-gaap_LiabilitiesFairValueDisclosure |
| Fair Value, Inputs, Level 1 [Member] | ||
| Trading securities | 523us-gaap_TradingSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
3,956us-gaap_TradingSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Available-for-sale Securities | 1us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
260us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Interest rate swap agreements | 0us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
0us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Other [assets] | 0us-gaap_OtherAssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
0us-gaap_OtherAssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Fair Value, Assets Measured on Recurring Basis, Total | 524us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
4,216us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Derivative component of prepaid forward sale agreements and indexed debt instruments | 0cmcsa_DerivativeFairValueOfEmbeddedDerivativeLiabilityComponentOfPrepaidForwardSaleAgreementsAndIndexedDebtInstruments / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
0cmcsa_DerivativeFairValueOfEmbeddedDerivativeLiabilityComponentOfPrepaidForwardSaleAgreementsAndIndexedDebtInstruments / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Contractual Obligation | 0us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
0us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Contingent consideration | 0us-gaap_BusinessCombinationContingentConsiderationLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
0us-gaap_BusinessCombinationContingentConsiderationLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Other [liabilities] | 0us-gaap_OtherLiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
0us-gaap_OtherLiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Fair Value Liabilities Measured On Recurring Basis | 0us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
0us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
| Fair Value, Inputs, Level 2 [Member] | ||
| Trading securities | 0us-gaap_TradingSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
0us-gaap_TradingSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Available-for-sale Securities | 121us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
118us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Interest rate swap agreements | 84us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
110us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Other [assets] | 64us-gaap_OtherAssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
80us-gaap_OtherAssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Fair Value, Assets Measured on Recurring Basis, Total | 269us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
308us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Derivative component of prepaid forward sale agreements and indexed debt instruments | 361cmcsa_DerivativeFairValueOfEmbeddedDerivativeLiabilityComponentOfPrepaidForwardSaleAgreementsAndIndexedDebtInstruments / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
2,816cmcsa_DerivativeFairValueOfEmbeddedDerivativeLiabilityComponentOfPrepaidForwardSaleAgreementsAndIndexedDebtInstruments / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Contractual Obligation | 0us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
0us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Contingent consideration | 0us-gaap_BusinessCombinationContingentConsiderationLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
0us-gaap_BusinessCombinationContingentConsiderationLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Other [liabilities] | 8us-gaap_OtherLiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
16us-gaap_OtherLiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Fair Value Liabilities Measured On Recurring Basis | 369us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
2,832us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
| Fair Value, Inputs, Level 3 [Member] | ||
| Trading securities | 0us-gaap_TradingSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
0us-gaap_TradingSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Available-for-sale Securities | 10us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
11us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Interest rate swap agreements | 0us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
0us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Other [assets] | 7us-gaap_OtherAssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
1us-gaap_OtherAssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Fair Value, Assets Measured on Recurring Basis, Total | 17us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
12us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Derivative component of prepaid forward sale agreements and indexed debt instruments | 0cmcsa_DerivativeFairValueOfEmbeddedDerivativeLiabilityComponentOfPrepaidForwardSaleAgreementsAndIndexedDebtInstruments / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
0cmcsa_DerivativeFairValueOfEmbeddedDerivativeLiabilityComponentOfPrepaidForwardSaleAgreementsAndIndexedDebtInstruments / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Contractual Obligation | 883us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
747us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Contingent consideration | 644us-gaap_BusinessCombinationContingentConsiderationLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
684us-gaap_BusinessCombinationContingentConsiderationLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Other [liabilities] | 0us-gaap_OtherLiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
0us-gaap_OtherLiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
| Fair Value Liabilities Measured On Recurring Basis | $ 1,527us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
$ 1,431us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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- Definition
This element represents the fair value as of the balance sheet date of embedded derivative liabilities as a component of prepaid forward sale agreements and indexed debt instruments valued on a recurring basis. No definition available.
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- Definition
Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of liability recognized arising from contingent consideration in a business combination. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fair value of obligations measured on a recurring basis. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fair value of financial and nonfinancial obligations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fair value portion of other assets. No definition available.
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- Definition
Fair value portion of other liabilities. No definition available.
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- Definition
Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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