v2.4.1.9

Goodwill Rollforward (Details) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013
Goodwill beginning balance | $ 27,098,000,000 us-gaap_Goodwill | $ 26,985,000,000 us-gaap_Goodwill
Acquisitions | 227,000,000 us-gaap_GoodwillAcquiredDuringPeriod | 42,000,000 us-gaap_GoodwillAcquiredDuringPeriod
Adjustments | (9,000,000)us-gaap_GoodwillOtherChanges | 71,000,000 us-gaap_GoodwillOtherChanges
Goodwill ending balance | 27,316,000,000 us-gaap_Goodwill | 27,098,000,000 us-gaap_Goodwill
NBCUniversal Media, LLC [Member] |  |
Goodwill beginning balance | 14,882,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 14,770,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Acquisitions | 35,000,000 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 42,000,000 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Adjustments | (9,000,000)us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 70,000,000 us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Goodwill ending balance | 14,908,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 14,882,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Cable Communications [Member] |  |
Goodwill beginning balance | 12,206,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 12,206,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Acquisitions | 11,000,000 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 0 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Adjustments | 0 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 0 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Goodwill ending balance | 12,217,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember | 12,206,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableCommunicationsMember
Cable Networks [Member] |  |
Goodwill beginning balance | 13,130,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 13,026,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Acquisitions | 20,000,000 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 39,000,000 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Adjustments | (202,000,000)us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 65,000,000 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Goodwill ending balance | 12,948,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 13,130,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Cable Networks [Member] | NBCUniversal Media, LLC [Member] |  |
Goodwill beginning balance | 13,130,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 13,026,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Acquisitions | 20,000,000 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 39,000,000 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Adjustments | (202,000,000)us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 65,000,000 us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Goodwill ending balance | 12,948,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember | 13,130,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_CableNetworksMember
Broadcast Television [Member] |  |
Goodwill beginning balance | 769,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 761,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Acquisitions | 0 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 3,000,000 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Adjustments | (2,000,000)us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 5,000,000 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Goodwill ending balance | 767,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 769,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Broadcast Television [Member] | NBCUniversal Media, LLC [Member] |  |
Goodwill beginning balance | 769,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 761,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Acquisitions | 0 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 3,000,000 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Adjustments | (2,000,000)us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 5,000,000 us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Goodwill ending balance | 767,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember | 769,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_BroadcastTelevisionMember
Filmed Entertainment [Member] |  |
Goodwill beginning balance | 1,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 1,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Acquisitions | 15,000,000 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 0 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Adjustments | 195,000,000 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 0 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Goodwill ending balance | 211,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 1,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Filmed Entertainment [Member] | NBCUniversal Media, LLC [Member] |  |
Goodwill beginning balance | 1,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 1,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Acquisitions | 15,000,000 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 0 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Adjustments | 195,000,000 us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 0 us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Goodwill ending balance | 211,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember | 1,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_FilmedEntertainmentMember
Theme Parks [Member] |  |
Goodwill beginning balance | 982,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 982,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Acquisitions | 0 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 0 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Adjustments | 0 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 0 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Goodwill ending balance | 982,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 982,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Theme Parks [Member] | NBCUniversal Media, LLC [Member] |  |
Goodwill beginning balance | 982,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 982,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Acquisitions | 0 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 0 us-gaap_GoodwillAcquiredDuringPeriod / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Adjustments | 0 us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 0 us-gaap_GoodwillOtherChanges / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Goodwill ending balance | 982,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember | 982,000,000 us-gaap_Goodwill / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember / us-gaap_StatementBusinessSegmentsAxis = cmcsa_ThemeParksMember
Corporate and Other [Member] |  |
Goodwill beginning balance | 10,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 9,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember
Acquisitions | 181,000,000 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 0 us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember
Adjustments | 0 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | 1,000,000 us-gaap_GoodwillOtherChanges / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember
Goodwill ending balance | $ 191,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember | $ 10,000,000 us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateAndOtherMember

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