|
Goodwill and Other Intangible Assets (Amortization of Intangible Assets) (Details) (USD $)
In Millions, unless otherwise specified |
Dec. 31, 2014
|
|---|---|
| Future amortization expense, 2015 | $ 1,619us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths |
| Future amortization expense, 2016 | 1,457us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo |
| Future amortization expense, 2017 | 1,296us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree |
| Future amortization expense, 2018 | 1,053us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour |
| Future amortization expense, 2019 | 842us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive |
| NBCUniversal Media, LLC [Member] | |
| Future amortization expense, 2015 | 777us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember |
| Future amortization expense, 2016 | 748us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember |
| Future amortization expense, 2017 | 747us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember |
| Future amortization expense, 2018 | 743us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember |
| Future amortization expense, 2019 | $ 740us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember |
| X | ||||||||||
|
- Definition
Amount of amortization expense expected to be recognized during the next fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Amount of amortization expense expected to be recognized during the fifth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Amount of amortization expense expected to be recognized during the fourth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Amount of amortization expense expected to be recognized during the third fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Amount of amortization expense expected to be recognized during the second fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|