v2.4.1.9
Commitments and Contingencies (Minimum Annual Commitments under the Programming License Agreements and Operating Leases) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Programming and talent commitments future minimum payments, 2015 $ 4,915cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsCurrent
Programming and talent commitments future minimum payments, 2016 4,657cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsInTwoYears
Programming and talent commitments future minimum payments, 2017 3,177cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsInThreeYears
Programming and talent commitments future minimum payments, 2018 3,999cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsInFourYears
Programming and talent commitments future minimum payments, 2019 2,793cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsInFiveYears
Programming and talent commitments future minimum payments, thereafter 26,130cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsDueThereafter
Operating leases future minimum payments, 2015 399us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent
Operating leases future minimum payments, 2016 359us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears
Operating leases future minimum payments, 2017 299us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears
Operating leases future minimum payments, 2018 253us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears
Operating leases future minimum payments, 2019 197us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears
Operating leases future minimum payments, thereafter 754us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter
NBCUniversal Media, LLC [Member]  
Programming and talent commitments future minimum payments, 2015 4,898cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsCurrent
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Programming and talent commitments future minimum payments, 2016 4,648cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsInTwoYears
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Programming and talent commitments future minimum payments, 2017 3,173cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsInThreeYears
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Programming and talent commitments future minimum payments, 2018 3,998cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsInFourYears
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Programming and talent commitments future minimum payments, 2019 2,793cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsInFiveYears
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Programming and talent commitments future minimum payments, thereafter 26,130cmcsa_ProgrammingAndTalentCommitmentsFutureMinimumPaymentsDueThereafter
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Operating leases future minimum payments, 2015 150us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Operating leases future minimum payments, 2016 135us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Operating leases future minimum payments, 2017 107us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Operating leases future minimum payments, 2018 89us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Operating leases future minimum payments, 2019 73us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember
Operating leases future minimum payments, thereafter $ 402us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter
/ cmcsa_LegalEntity1Axis
= cmcsa_NBCUniversalMediaLLCMember