v2.4.1.9

Long-Term Debt (Narrative) (Details) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013
Long-term Debt, Fair Value | $ 55,300,000,000 us-gaap_LongTermDebtFairValue | $ 51,800,000,000 us-gaap_LongTermDebtFairValue
Borrowing margin for LIBOR based borrowings | 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 |
Amounts available under revolving credit facilities | 6,500,000,000 us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity |
Unused irrevocable standby letters of credit | 473,000,000 us-gaap_LettersOfCreditOutstandingAmount |
Commercial paper | 845,000,000 us-gaap_CommercialPaper | 1,350,000,000 us-gaap_CommercialPaper
NBCUniversal Media, LLC [Member] |  |
Long-term Debt, Fair Value | 11,500,000,000 us-gaap_LongTermDebtFairValue / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember | 11,700,000,000 us-gaap_LongTermDebtFairValue / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember
Comcast And Comcast Cable Communications LLC [Member] |  |
Debt Instrument, Maturity Date, Description | June 2017 |
Credit facility borrowing capacity | 6,250,000,000 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / dei_LegalEntityAxis = cmcsa_ComcastAndComcastCableCommunicationsLlcMember |
NBCUniversal Enterprise [Member] | NBCUniversal Media, LLC [Member] |  |
Principal amount | 4,000,000,000 us-gaap_DebtInstrumentFaceAmount / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseMember |
Preferred stock liquidition preference value | 725,000,000 us-gaap_PreferredStockLiquidationPreferenceValue / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseMember |
NBCUniversal Enterprise Commercial Paper [Member] |  |
Credit facility borrowing capacity | 1,350,000,000 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseCommercialPaperMember |
Comcast And Comcast Cable Revolving Credit Facility [Member] | NBCUniversal Media, LLC [Member] |  |
Guarantee Obligations Current Principal Balance | 6,250,000,000 cmcsa_GuaranteeObligationsCurrentPrincipalBalance / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_ComcastAndComcastCableRevolvingCreditFacilityMember |
Debt Instrument, Maturity Date, Description | June 2017 |
Comcast And Comcast Cable Debt Securities [Member] | NBCUniversal Media, LLC [Member] |  |
Guarantee Obligations Current Principal Balance | 32,600,000,000 cmcsa_GuaranteeObligationsCurrentPrincipalBalance / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_ComcastAndComcastCableDebtSecuritiesMember |
NBCUniversal Enterprise Credit Facility [Member] |  |
Debt Instrument, Maturity Date, Description | March 2018 |
Borrowing margin for LIBOR based borrowings | 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseCreditFacilityMember |
Credit facility borrowing capacity | 1,350,000,000 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseCreditFacilityMember |
Amounts available under revolving credit facilities | 505,000,000 us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseCreditFacilityMember |
NBCUniversal Enterprise Credit Facility [Member] | NBCUniversal Media, LLC [Member] |  |
Credit facility borrowing capacity | $ 1,350,000,000 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseCreditFacilityMember |

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- Definition Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(a)(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.13(2)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19 -Subparagraph a(3) -Article 5 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 13 -Subparagraph 2 -Article 9 + Details
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- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400 + Details
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- Definition Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
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- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
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- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
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- Definition Value of the difference between preference in liquidation and the par or stated values of the preferred shares. + References No definition available. + Details
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