v2.4.1.9

Related Party Transactions - Consolidated Statement of Income (Details) (USD $) | 3 Months Ended
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Mar. 31, 2015 | Mar. 31, 2014
Revenue | $ 17,853,000,000 us-gaap_Revenues | $ 17,408,000,000 us-gaap_Revenues
NBCUniversal Media, LLC [Member] |  |
Revenue | 6,604,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 6,876,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Transactions With Comcast And Consolidated Subsidiaries [Member] | NBCUniversal Media, LLC [Member] |  |
Revenue | 342,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = cmcsa_ComcastAndConsolidatedSubsidiariesMember | 361,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = cmcsa_ComcastAndConsolidatedSubsidiariesMember
Operating costs and expenses | (50,000,000)cmcsa_OperatingExpensesExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = cmcsa_ComcastAndConsolidatedSubsidiariesMember | (37,000,000)cmcsa_OperatingExpensesExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = cmcsa_ComcastAndConsolidatedSubsidiariesMember
Other income (expense) | $ (9,000,000)cmcsa_OtherIncomeExpenseRelatedParty / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = cmcsa_ComcastAndConsolidatedSubsidiariesMember | $ (9,000,000)cmcsa_OtherIncomeExpenseRelatedParty / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = cmcsa_ComcastAndConsolidatedSubsidiariesMember

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- Definition Operating costs and expenses including amortization of film and television costs but excluding intangible amortization and depreciation. + References No definition available. + Details
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Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Represents all of the intercompany transactions with Comcast Corporation which are included in other income (expense) captions. + References No definition available. + Details
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- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Article 5 + Details
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- Details
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- Details
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