XML 69 R9.htm IDEA: XBRL DOCUMENT v2.4.1.9
Consolidated Statement of Changes in Equity (USD $)
In Millions
Total
NBCUniversal Media, LLC [Member]
Redeemable Noncontrolling Interests And Redeemable Subisdiary Preferred Stock [Member]
Class A Common Stock [Member]
Class A Special Common Stock [Member]
Class B Common Stock [Member]
Additional Paid-In Capital [Member]
Retained Earnings [Member]
Treasury Stock at Cost [Member]
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Member]
NBCUniversal Media, LLC [Member]
Noncontrolling Interests [Member]
Noncontrolling Interests [Member]
NBCUniversal Media, LLC [Member]
Redeemable Noncontrolling Interest [Member]
NBCUniversal Media, LLC [Member]
Member's Capital [Member]
NBCUniversal Media, LLC [Member]
Beginning balance at Dec. 31, 2011   $ 30,081us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                $ (78)us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
  $ 361us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
$ 184us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
$ 29,798us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Beginning Balance at Dec. 31, 2011 47,655us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest   16,014us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
25us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonClassAMember
7us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_ClassaSpecialCommonStockMember
0us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonClassBMember
40,940us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
13,971us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
(7,517)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_TreasuryStockMember
(152)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
  381us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
     
Stock compensation plans 372us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation           612us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
(240)us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
             
Repurchases and retirements of common stock (3,000)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue       (1)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_ClassaSpecialCommonStockMember
  (1,081)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
(1,918)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
             
Employee stock purchase plans 80us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan           80us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
               
Compensation Plans   7us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                        7us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Other comprehensive income (loss) 167us-gaap_OtherComprehensiveIncomeLossNetOfTax 13us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
6us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
            167us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
13us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
       
Redemption transaction distribution   0cmcsa_RedemptionTransactionDistribution
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                         
Dividends declared (1,736)us-gaap_DividendsCommonStockCash (964)us-gaap_DividendsCommonStockCash
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
          (1,736)us-gaap_DividendsCommonStockCash
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
            (964)us-gaap_DividendsCommonStockCash
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Purchase of subsidiary shares from noncontrolling interests                           (47)cmcsa_NoncontrollingInterestDecreaseFromRedemptionsOrPurchaseOfInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
 
Contributions from and (distributions to) noncontrolling interests, net (169)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests (184)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
(493)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
                (169)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(184)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(24)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
 
Other 76us-gaap_StockholdersEquityOther 88us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
(43)us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
      (4)us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
        80us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
84us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  4us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Net income (loss) 6,351cmcsa_EquityProfitLoss 3,213cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
1,514cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
        6,203cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
      148cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
158cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
18cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
3,055cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Ending Balance at Dec. 31, 2012 49,796us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest   16,998us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
25us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonClassAMember
6us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_ClassaSpecialCommonStockMember
0us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonClassBMember
40,547us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
16,280us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
(7,517)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_TreasuryStockMember
15us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
  440us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
     
Ending balance at Dec. 31, 2012   32,254us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                (65)us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
  419us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
131us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
31,900us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Stock compensation plans 232us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation            603us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
(371)us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
             
Repurchases and retirements of common stock (2,000)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue       (1)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_ClassaSpecialCommonStockMember
  (555)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
(1,444)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
             
Employee stock purchase plans 98us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan           98us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
               
Compensation Plans   7us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                        7us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Other comprehensive income (loss) 67us-gaap_OtherComprehensiveIncomeLossNetOfTax 49us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
(9)us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
            67us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
49us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
       
Redemption transaction distribution   (3,200)cmcsa_RedemptionTransactionDistribution
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                        (3,200)cmcsa_RedemptionTransactionDistribution
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Dividends declared (2,046)us-gaap_DividendsCommonStockCash (1,422)us-gaap_DividendsCommonStockCash
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
          (2,046)us-gaap_DividendsCommonStockCash
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
            (1,422)us-gaap_DividendsCommonStockCash
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Purchase of NBCUniversal noncontrolling common equity interest (1,677)cmcsa_PurchaseOfNoncontrollingCommonEquityInterest   (17,006)cmcsa_PurchaseOfNoncontrollingCommonEquityInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
      (1,651)cmcsa_PurchaseOfNoncontrollingCommonEquityInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
    (26)cmcsa_PurchaseOfNoncontrollingCommonEquityInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
         
Purchase of subsidiary shares from noncontrolling interests   (33)cmcsa_NoncontrollingInterestDecreaseFromRedemptionsOrPurchaseOfInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                        (33)cmcsa_NoncontrollingInterestDecreaseFromRedemptionsOrPurchaseOfInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Redeemable subsidiary preferred stock     725cmcsa_SubsidiaryPreferredStock
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
                       
Contributions from and (distributions to) noncontrolling interests, net (136)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests (155)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
(22)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
                (136)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(155)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(22)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
 
Other (210)us-gaap_StockholdersEquityOther (275)us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
70us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
      (152)us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
        (58)us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(111)us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
102us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
(164)us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Net income (loss) 6,934cmcsa_EquityProfitLoss 2,102cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
201cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
        6,816cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
      118cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
134cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
20cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
1,968cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Ending Balance at Dec. 31, 2013 51,058us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest   957us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
25us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonClassAMember
5us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_ClassaSpecialCommonStockMember
0us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonClassBMember
38,890us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
19,235us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
(7,517)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_TreasuryStockMember
56us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
  364us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
     
Ending balance at Dec. 31, 2013   29,327us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                (16)us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
  287us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
231us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
29,056us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Stock compensation plans 299us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation           732us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
(433)us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
             
Repurchases and retirements of common stock (4,251)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue           (928)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
(3,323)us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
             
Employee stock purchase plans 118us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan           118us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
               
Other comprehensive income (loss) (202)us-gaap_OtherComprehensiveIncomeLossNetOfTax (143)us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
              (202)us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
(143)us-gaap_OtherComprehensiveIncomeLossNetOfTax
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
       
Redemption transaction distribution   0cmcsa_RedemptionTransactionDistribution
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                         
Dividends declared (2,320)us-gaap_DividendsCommonStockCash (1,641)us-gaap_DividendsCommonStockCash
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
          (2,320)us-gaap_DividendsCommonStockCash
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
            (1,641)us-gaap_DividendsCommonStockCash
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Issuance of subsidiary shares to noncontrolling interests 11cmcsa_NoncontrollingInterestIncreaseFromEquityIssuanceOrSaleOfParentEquityInterest   85cmcsa_NoncontrollingInterestIncreaseFromEquityIssuanceOrSaleOfParentEquityInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
                11cmcsa_NoncontrollingInterestIncreaseFromEquityIssuanceOrSaleOfParentEquityInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  85cmcsa_NoncontrollingInterestIncreaseFromEquityIssuanceOrSaleOfParentEquityInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
 
Contributions from and (distributions to) noncontrolling interests, net (132)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests (152)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
(19)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
                (132)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(152)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(24)cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
 
Other (29)us-gaap_StockholdersEquityOther (13)us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
(33)us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
      (7)us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
        (22)us-gaap_StockholdersEquityOther
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
(12)us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
  (1)us-gaap_StockholdersEquityOther
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Net income (loss) 8,516cmcsa_EquityProfitLoss 3,259cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
76cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
        8,380cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
      136cmcsa_EquityProfitLoss
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
144cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
38cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
3,115cmcsa_EquityProfitLoss
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember
Ending Balance at Dec. 31, 2014 53,068us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest   1,066us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestsAndRedeemableSubisdiaryPreferredStockMember
25us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonClassAMember
5us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_ClassaSpecialCommonStockMember
0us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonClassBMember
38,805us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AdditionalPaidInCapitalMember
21,539us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_RetainedEarningsMember
(7,517)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_TreasuryStockMember
(146)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
  357us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
     
Ending balance at Dec. 31, 2014   $ 30,637us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
                $ (159)us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
  $ 267us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_NoncontrollingInterestMember
$ 330us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_RedeemableNoncontrollingInterestMember
$ 30,529us-gaap_LimitedLiabilityCompanyLlcMembersEquityIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= cmcsa_NBCUniversalMediaLLCMember
/ us-gaap_StatementEquityComponentsAxis
= cmcsa_MembersCapitalMember