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Long-Term Debt (Narrative) (Details) (USD $)
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3 Months Ended |
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Mar. 31, 2015
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| Total debt | $ 47,100,000,000us-gaap_DebtAndCapitalLeaseObligations |
| Long-term Debt, Fair Value | 54,900,000,000us-gaap_LongTermDebtFairValue |
| Amounts available under revolving credit facilities | 6,600,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity |
| NBCUniversal Media, LLC [Member] | |
| Total debt | 10,200,000,000us-gaap_DebtAndCapitalLeaseObligations / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember |
| Long-term Debt, Fair Value | 11,600,000,000us-gaap_LongTermDebtFairValue / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember |
| Comcast ownership in cable holding company subsidiaries | 100.00%cmcsa_ComcastOwnershipInCableHoldingCompanySubsidiaries / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember |
| NBCUniversal Enterprise [Member] | |
| Commercial paper | 700,000,000us-gaap_CommercialPaper / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseMember |
| NBCUniversal Enterprise [Member] | NBCUniversal Media, LLC [Member] | |
| Principal amount | 4,000,000,000us-gaap_DebtInstrumentFaceAmount / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseMember |
| Preferred stock liquidation preference value | 725,000,000us-gaap_PreferredStockLiquidationPreferenceValue / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseMember |
| Guarantee Obligations Current Principal Balance | 1,350,000,000cmcsa_GuaranteeObligationsCurrentPrincipalBalance / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseMember |
| Comcast And Comcast Cable Revolving Credit Facility [Member] | NBCUniversal Media, LLC [Member] | |
| Debt Instrument, Maturity Date, Description | 2017 |
| Revolver Line of credit amount outstanding | 0us-gaap_LineOfCredit / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_ComcastAndComcastCableRevolvingCreditFacilityMember |
| Guarantee Obligations Current Principal Balance | 6,250,000,000cmcsa_GuaranteeObligationsCurrentPrincipalBalance / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_ComcastAndComcastCableRevolvingCreditFacilityMember |
| Comcast And Comcast Cable Debt Securities [Member] | NBCUniversal Media, LLC [Member] | |
| Guarantee Obligations Current Principal Balance | 31,700,000,000cmcsa_GuaranteeObligationsCurrentPrincipalBalance / cmcsa_LegalEntity1Axis = cmcsa_NBCUniversalMediaLLCMember / dei_LegalEntityAxis = cmcsa_ComcastAndComcastCableDebtSecuritiesMember |
| NBCUniversal Enterprise Credit Facility [Member] | |
| Amounts available under revolving credit facilities | $ 650,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity / dei_LegalEntityAxis = cmcsa_NbcuniversalEnterpriseCreditFacilityMember |
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Represents the Company's ownership in its cable holding company subsidiaries. No definition available.
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Principal amount of debt securities subject to guarantee. No definition available.
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Face (par) amount of debt instrument at time of issuance. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. No definition available.
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Value of the difference between preference in liquidation and the par or stated values of the preferred shares. No definition available.
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