v2.4.1.9

Financial Data by Business Segment (Details) (USD $) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Revenue | $ 17,732,000,000 us-gaap_Revenues | $ 16,791,000,000 us-gaap_Revenues | $ 16,844,000,000 us-gaap_Revenues | $ 17,408,000,000 us-gaap_Revenues | $ 16,926,000,000 us-gaap_Revenues | $ 16,151,000,000 us-gaap_Revenues | $ 16,270,000,000 us-gaap_Revenues | $ 15,310,000,000 us-gaap_Revenues | $ 68,775,000,000 us-gaap_Revenues | $ 64,657,000,000 us-gaap_Revenues | $ 62,570,000,000 us-gaap_Revenues
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 22,923,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization | 21,434,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization | 19,977,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization
Depreciation and amortization |  |  |  |  |  |  |  |  | 8,019,000,000 us-gaap_DepreciationAndAmortization | 7,871,000,000 us-gaap_DepreciationAndAmortization | 7,798,000,000 us-gaap_DepreciationAndAmortization
Operating income (loss) | 3,787,000,000 us-gaap_OperatingIncomeLoss | 3,745,000,000 us-gaap_OperatingIncomeLoss | 3,804,000,000 us-gaap_OperatingIncomeLoss | 3,568,000,000 us-gaap_OperatingIncomeLoss | 3,647,000,000 us-gaap_OperatingIncomeLoss | 3,414,000,000 us-gaap_OperatingIncomeLoss | 3,435,000,000 us-gaap_OperatingIncomeLoss | 3,067,000,000 us-gaap_OperatingIncomeLoss | 14,904,000,000 us-gaap_OperatingIncomeLoss | 13,563,000,000 us-gaap_OperatingIncomeLoss | 12,179,000,000 us-gaap_OperatingIncomeLoss
Capital expenditures |  |  |  |  |  |  |  |  | 7,420,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment | 6,596,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment | 5,714,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Assets | 159,339,000,000 us-gaap_Assets |  |  |  | 158,813,000,000 us-gaap_Assets |  |  |  | 159,339,000,000 us-gaap_Assets | 158,813,000,000 us-gaap_Assets |
NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 25,428,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 23,650,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 23,812,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 5,588,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 4,732,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 4,107,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 1,495,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 1,411,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 1,326,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Operating income (loss) |  |  |  |  |  |  |  |  | 4,093,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 3,321,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 2,781,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Capital expenditures |  |  |  |  |  |  |  |  | 1,221,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 1,160,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 763,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Assets | 52,617,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember |  |  |  | 51,739,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember |  |  |  | 52,617,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 51,739,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember |
Non U S Customers [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 4,400,000,000 us-gaap_Revenues / us-gaap_StatementGeographicalAxis = cmcsa_NonUSCustomersMember | 4,800,000,000 us-gaap_Revenues / us-gaap_StatementGeographicalAxis = cmcsa_NonUSCustomersMember | 4,500,000,000 us-gaap_Revenues / us-gaap_StatementGeographicalAxis = cmcsa_NonUSCustomersMember
Non U S Customers [Member] | NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 4,433,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementGeographicalAxis = cmcsa_NonUSCustomersMember | 4,763,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementGeographicalAxis = cmcsa_NonUSCustomersMember | 4,464,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementGeographicalAxis = cmcsa_NonUSCustomersMember
United States [Member] | NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 20,995,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementGeographicalAxis = cmcsa_UnitedStatesMember | 18,887,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementGeographicalAxis = cmcsa_UnitedStatesMember | 19,348,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementGeographicalAxis = cmcsa_UnitedStatesMember
Cable Communications [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 44,140,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 41,836,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 39,604,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 18,112,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 17,205,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 16,255,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 6,422,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 6,394,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 6,405,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Operating income (loss) |  |  |  |  |  |  |  |  | 11,690,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 10,811,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 9,850,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Capital expenditures |  |  |  |  |  |  |  |  | 6,154,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 5,403,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 4,921,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Cable segment revenue types as percentage of total cable revenue |  |  |  |  |  |  |  |  | 100.00%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 100.00%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 100.00%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Assets | 140,616,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember |  |  |  | 132,082,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember |  |  |  | 140,616,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 132,082,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember |
Cable Networks [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 9,563,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 9,201,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 8,727,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 3,589,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 3,501,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 3,303,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 748,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 734,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 735,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Operating income (loss) |  |  |  |  |  |  |  |  | 2,841,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 2,767,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 2,568,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Capital expenditures |  |  |  |  |  |  |  |  | 49,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 67,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 150,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Assets | 28,582,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember |  |  |  | 29,413,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember |  |  |  | 28,582,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 29,413,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember |
Cable Networks [Member] | NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 9,563,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 9,201,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 8,727,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 3,589,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 3,501,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 3,303,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 748,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 734,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 735,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Operating income (loss) |  |  |  |  |  |  |  |  | 2,841,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 2,767,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 2,568,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Capital expenditures |  |  |  |  |  |  |  |  | 49,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 67,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 150,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Assets | 28,582,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember |  |  |  | 29,413,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember |  |  |  | 28,582,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 29,413,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember |
Broadcast Television [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 8,542,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 7,120,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 8,200,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 734,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 345,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 358,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 127,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 98,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 97,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Operating income (loss) |  |  |  |  |  |  |  |  | 607,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 247,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 261,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Capital expenditures |  |  |  |  |  |  |  |  | 76,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 65,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 65,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Assets | 6,806,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember |  |  |  | 6,723,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember |  |  |  | 6,806,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 6,723,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember |
Broadcast Television [Member] | NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 8,542,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 7,120,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 8,200,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 734,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 345,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 358,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 127,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 98,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 97,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Operating income (loss) |  |  |  |  |  |  |  |  | 607,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 247,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 261,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Capital expenditures |  |  |  |  |  |  |  |  | 76,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 65,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 65,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Assets | 6,806,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember |  |  |  | 6,723,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember |  |  |  | 6,806,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 6,723,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember |
Filmed Entertainment [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 5,008,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 5,452,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 5,159,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 711,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 483,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 79,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 21,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 15,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 16,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Operating income (loss) |  |  |  |  |  |  |  |  | 690,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 468,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 63,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Capital expenditures |  |  |  |  |  |  |  |  | 11,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 9,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 7,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Assets | 4,185,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember |  |  |  | 3,549,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember |  |  |  | 4,185,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 3,549,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember |
Filmed Entertainment [Member] | NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 5,008,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 5,452,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 5,159,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 711,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 483,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 79,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 21,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 15,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 16,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Operating income (loss) |  |  |  |  |  |  |  |  | 690,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 468,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 63,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Capital expenditures |  |  |  |  |  |  |  |  | 11,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 9,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 7,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Assets | 4,185,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember |  |  |  | 3,549,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember |  |  |  | 4,185,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 3,549,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember |
Theme Parks [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 2,623,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 2,235,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 2,085,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 1,168,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 1,004,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 953,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 273,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 300,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 268,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Operating income (loss) |  |  |  |  |  |  |  |  | 895,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 704,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 685,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Capital expenditures |  |  |  |  |  |  |  |  | 671,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 580,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 272,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Assets | 7,017,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember |  |  |  | 6,608,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember |  |  |  | 7,017,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 6,608,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember |
Theme Parks [Member] | NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 2,623,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 2,235,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 2,085,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 1,168,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 1,004,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 953,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 273,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 300,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 268,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Operating income (loss) |  |  |  |  |  |  |  |  | 895,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 704,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 685,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Capital expenditures |  |  |  |  |  |  |  |  | 671,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 580,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 272,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Assets | 7,017,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember |  |  |  | 6,608,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember |  |  |  | 7,017,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 6,608,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember |
Headquarters And Other [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 13,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 31,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 43,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | (613,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | (588,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | (603,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 326,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 264,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 210,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Operating income (loss) |  |  |  |  |  |  |  |  | (939,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | (852,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | (813,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Capital expenditures |  |  |  |  |  |  |  |  | 414,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 439,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 269,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Assets | 6,479,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember |  |  |  | 6,002,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember |  |  |  | 6,479,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 6,002,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember |
Headquarters And Other [Member] | NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 13,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 31,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 43,000,000 us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | (613,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | (588,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | (603,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 326,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 264,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 210,000,000 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Operating income (loss) |  |  |  |  |  |  |  |  | (939,000,000)us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | (852,000,000)us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | (813,000,000)us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Capital expenditures |  |  |  |  |  |  |  |  | 414,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 439,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 269,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember
Assets | 6,479,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember |  |  |  | 6,002,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember |  |  |  | 6,479,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember | 6,002,000,000 us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_HeadquartersAndOtherMember |
NBCUniversal Eliminations [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | (321,000,000)us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (389,000,000)us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (402,000,000)us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | (1,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (13,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 17,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 0 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 0 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 0 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Operating income (loss) |  |  |  |  |  |  |  |  | (1,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (13,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 17,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Capital expenditures |  |  |  |  |  |  |  |  | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Assets | (452,000,000)us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember |  |  |  | (556,000,000)us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember |  |  |  | (452,000,000)us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (556,000,000)us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember |
NBCUniversal Eliminations [Member] | NBCUniversal Media, LLC [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | (321,000,000)us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (389,000,000)us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (402,000,000)us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | (1,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (13,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 17,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 0 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 0 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 0 us-gaap_DepreciationAndAmortization / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Operating income (loss) |  |  |  |  |  |  |  |  | (1,000,000)us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (13,000,000)us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 17,000,000 us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Capital expenditures |  |  |  |  |  |  |  |  | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember
Assets | (452,000,000)us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember |  |  |  | (556,000,000)us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember |  |  |  | (452,000,000)us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember | (556,000,000)us-gaap_Assets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalEliminationsMember |
NBCUniversal [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 25,428,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 23,650,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 23,812,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 5,588,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 4,732,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 4,107,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 1,495,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 1,411,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 1,326,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember
Operating income (loss) |  |  |  |  |  |  |  |  | 4,093,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 3,321,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 2,781,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember
Capital expenditures |  |  |  |  |  |  |  |  | 1,221,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 1,160,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 763,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember
Assets | 52,617,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember |  |  |  | 51,739,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember |  |  |  | 52,617,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember | 51,739,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_NbcuniversalMember |
Corporate and Other [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 709,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 600,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 498,000,000 us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | (778,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | (489,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | (376,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 102,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 66,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 67,000,000 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember
Operating income (loss) |  |  |  |  |  |  |  |  | (880,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | (555,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | (443,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember
Capital expenditures |  |  |  |  |  |  |  |  | 45,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 33,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 30,000,000 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember
Assets | 5,338,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember |  |  |  | 8,152,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember |  |  |  | 5,338,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 8,152,000,000 us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember |
Eliminations [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | (1,502,000,000)us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | (1,429,000,000)us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | (1,344,000,000)us-gaap_Revenues / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember
Operating income (loss) before depreciation and amortization |  |  |  |  |  |  |  |  | 1,000,000 cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | (14,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | (9,000,000)cmcsa_OperatingIncomeExcludingDepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember
Depreciation and amortization |  |  |  |  |  |  |  |  | 0 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | 0 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | 0 us-gaap_DepreciationAndAmortization / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember
Operating income (loss) |  |  |  |  |  |  |  |  | 1,000,000 us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | (14,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | (9,000,000)us-gaap_OperatingIncomeLoss / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember
Capital expenditures |  |  |  |  |  |  |  |  | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember
Assets | $ (39,232,000,000)us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember |  |  |  | $ (33,160,000,000)us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember |  |  |  | $ (39,232,000,000)us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember | $ (33,160,000,000)us-gaap_Assets / us-gaap_StatementBusinessSegmentsAxis = cmcsa_EliminationsMember |
Cable Communications Segment Revenue Percentage-Video [Member] |  |  |  |  |  |  |  |  |  |  |
Cable segment revenue types as percentage of total cable revenue |  |  |  |  |  |  |  |  | 47.10%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageVideoMember | 49.10%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageVideoMember | 50.40%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageVideoMember
Cable Communications Segment Revenue Percentage - High-speed Internet [Member] |  |  |  |  |  |  |  |  |  |  |
Cable segment revenue types as percentage of total cable revenue |  |  |  |  |  |  |  |  | 25.60%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageHighSpeedInternetMember | 24.70%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageHighSpeedInternetMember | 24.10%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageHighSpeedInternetMember
Cable Communications Segment Revenue Percentage- Voice [Member] |  |  |  |  |  |  |  |  |  |  |
Cable segment revenue types as percentage of total cable revenue |  |  |  |  |  |  |  |  | 8.30%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageVoiceMember | 8.70%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageVoiceMember | 9.00%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageVoiceMember
Cable Communications Segment Revenue Percentage- Business Services [Member] |  |  |  |  |  |  |  |  |  |  |
Cable segment revenue types as percentage of total cable revenue |  |  |  |  |  |  |  |  | 9.00%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageBusinessServicesMember | 7.70%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageBusinessServicesMember | 6.50%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageBusinessServicesMember
Cable Communications Segment Revenue Percentage- Advertising [Member] |  |  |  |  |  |  |  |  |  |  |
Cable segment revenue types as percentage of total cable revenue |  |  |  |  |  |  |  |  | 5.50%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageAdvertisingMember | 5.20%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageAdvertisingMember | 5.80%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageAdvertisingMember
Cable Communications Segment Revenue Percentage- Other [Member] |  |  |  |  |  |  |  |  |  |  |
Cable segment revenue types as percentage of total cable revenue |  |  |  |  |  |  |  |  | 4.50%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageOtherMember | 4.60%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageOtherMember | 4.20%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageOtherMember
Cable Communications Segment Revenue Percentage- Franchise and other regulatory fees [Member] |  |  |  |  |  |  |  |  |  |  |
Cable segment revenue types as percentage of total cable revenue |  |  |  |  |  |  |  |  | 2.80%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageFranchiseFeesMember | 2.80%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageFranchiseFeesMember | 2.80%cmcsa_CableSegmentRevenueTypesAsPercentageOfTotalCableRevenue / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsSegmentRevenuePercentageFranchiseFeesMember

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