v2.4.1.9

Consolidated Statement of Income (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
Costs and Expenses: |  |  |  |  |  |  |  |  |  |  |
Programming and production |  |  |  |  |  |  |  |  | 20,912,000,000 cmcsa_ProgrammingAndProductionCosts | 19,670,000,000 cmcsa_ProgrammingAndProductionCosts | 19,929,000,000 cmcsa_ProgrammingAndProductionCosts
Other operating and administrative |  |  |  |  |  |  |  |  | 19,862,000,000 cmcsa_OtherOperatingAndAdministrative | 18,584,000,000 cmcsa_OtherOperatingAndAdministrative | 17,833,000,000 cmcsa_OtherOperatingAndAdministrative
Advertising, marketing and promotion |  |  |  |  |  |  |  |  | 5,078,000,000 us-gaap_MarketingAndAdvertisingExpense | 4,969,000,000 us-gaap_MarketingAndAdvertisingExpense | 4,831,000,000 us-gaap_MarketingAndAdvertisingExpense
Depreciation |  |  |  |  |  |  |  |  | 6,337,000,000 us-gaap_Depreciation | 6,254,000,000 us-gaap_Depreciation | 6,150,000,000 us-gaap_Depreciation
Amortization |  |  |  |  |  |  |  |  | 1,682,000,000 us-gaap_AmortizationOfIntangibleAssets | 1,617,000,000 us-gaap_AmortizationOfIntangibleAssets | 1,648,000,000 us-gaap_AmortizationOfIntangibleAssets
Total costs and expenses |  |  |  |  |  |  |  |  | 53,871,000,000 us-gaap_CostsAndExpenses | 51,094,000,000 us-gaap_CostsAndExpenses | 50,391,000,000 us-gaap_CostsAndExpenses
Operating income | 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
Other Income (Expense): |  |  |  |  |  |  |  |  |  |  |
Interest expense |  |  |  |  |  |  |  |  | (2,617,000,000)us-gaap_InterestExpense | (2,574,000,000)us-gaap_InterestExpense | (2,521,000,000)us-gaap_InterestExpense
Investment income (loss), net |  |  |  |  |  |  |  |  | 296,000,000 us-gaap_InvestmentIncomeNonoperating | 576,000,000 us-gaap_InvestmentIncomeNonoperating | 219,000,000 us-gaap_InvestmentIncomeNonoperating
Equity in net income (losses) of investees, net |  |  |  |  |  |  |  |  | 97,000,000 us-gaap_IncomeLossFromEquityMethodInvestments | (86,000,000)us-gaap_IncomeLossFromEquityMethodInvestments | 959,000,000 us-gaap_IncomeLossFromEquityMethodInvestments
Other income (expense), net |  |  |  |  |  |  |  |  | (215,000,000)us-gaap_OtherNonoperatingIncomeExpense | (364,000,000)us-gaap_OtherNonoperatingIncomeExpense | 773,000,000 us-gaap_OtherNonoperatingIncomeExpense
Nonoperating income (expense) |  |  |  |  |  |  |  |  | (2,439,000,000)us-gaap_NonoperatingIncomeExpense | (2,448,000,000)us-gaap_NonoperatingIncomeExpense | (570,000,000)us-gaap_NonoperatingIncomeExpense
Income before income taxes |  |  |  |  |  |  |  |  | 12,465,000,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | 11,115,000,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | 11,609,000,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Income tax expense |  |  |  |  |  |  |  |  | (3,873,000,000)us-gaap_IncomeTaxExpenseBenefit | (3,980,000,000)us-gaap_IncomeTaxExpenseBenefit | (3,744,000,000)us-gaap_IncomeTaxExpenseBenefit
Net income |  |  |  |  |  |  |  |  | 8,592,000,000 us-gaap_ProfitLoss | 7,135,000,000 us-gaap_ProfitLoss | 7,865,000,000 us-gaap_ProfitLoss
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock |  |  |  |  |  |  |  |  | (212,000,000)cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock | (319,000,000)cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock | (1,662,000,000)cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock
Net income attributable to Parent | 1,925,000,000 us-gaap_NetIncomeLoss | 2,592,000,000 us-gaap_NetIncomeLoss | 1,992,000,000 us-gaap_NetIncomeLoss | 1,871,000,000 us-gaap_NetIncomeLoss | 1,913,000,000 us-gaap_NetIncomeLoss | 1,732,000,000 us-gaap_NetIncomeLoss | 1,734,000,000 us-gaap_NetIncomeLoss | 1,437,000,000 us-gaap_NetIncomeLoss | 8,380,000,000 us-gaap_NetIncomeLoss | 6,816,000,000 us-gaap_NetIncomeLoss | 6,203,000,000 us-gaap_NetIncomeLoss
Basic earnings per common share attributable to Comcast Corporation shareholders | $ 0.75 us-gaap_EarningsPerShareBasic | $ 1 us-gaap_EarningsPerShareBasic | $ 0.77 us-gaap_EarningsPerShareBasic | $ 0.72 us-gaap_EarningsPerShareBasic | $ 0.73 us-gaap_EarningsPerShareBasic | $ 0.66 us-gaap_EarningsPerShareBasic | $ 0.66 us-gaap_EarningsPerShareBasic | $ 0.55 us-gaap_EarningsPerShareBasic | $ 3.24 us-gaap_EarningsPerShareBasic | $ 2.6 us-gaap_EarningsPerShareBasic | $ 2.32 us-gaap_EarningsPerShareBasic
Diluted earnings per common share attributable to Comcast Corporation shareholders | $ 0.74 us-gaap_EarningsPerShareDiluted | $ 0.99 us-gaap_EarningsPerShareDiluted | $ 0.76 us-gaap_EarningsPerShareDiluted | $ 0.71 us-gaap_EarningsPerShareDiluted | $ 0.72 us-gaap_EarningsPerShareDiluted | $ 0.65 us-gaap_EarningsPerShareDiluted | $ 0.65 us-gaap_EarningsPerShareDiluted | $ 0.54 us-gaap_EarningsPerShareDiluted | $ 3.2 us-gaap_EarningsPerShareDiluted | $ 2.56 us-gaap_EarningsPerShareDiluted | $ 2.28 us-gaap_EarningsPerShareDiluted
Dividends declared per common share | $ 0.225 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.225 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.225 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.225 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.195 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.195 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.195 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.195 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.9 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.78 us-gaap_CommonStockDividendsPerShareDeclared | $ 0.65 us-gaap_CommonStockDividendsPerShareDeclared
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
Costs and Expenses: |  |  |  |  |  |  |  |  |  |  |
Programming and production |  |  |  |  |  |  |  |  | 12,318,000,000 cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 11,770,000,000 cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 12,710,000,000 cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Other operating and administrative |  |  |  |  |  |  |  |  | 5,364,000,000 cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 4,949,000,000 cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 4,763,000,000 cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Advertising, marketing and promotion |  |  |  |  |  |  |  |  | 2,158,000,000 us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 2,199,000,000 us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 2,232,000,000 us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Depreciation |  |  |  |  |  |  |  |  | 654,000,000 us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 639,000,000 us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 562,000,000 us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Amortization |  |  |  |  |  |  |  |  | 841,000,000 us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 772,000,000 us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 764,000,000 us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Total costs and expenses |  |  |  |  |  |  |  |  | 21,335,000,000 us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 20,329,000,000 us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 21,031,000,000 us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Operating income |  |  |  |  |  |  |  |  | 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
Other Income (Expense): |  |  |  |  |  |  |  |  |  |  |
Interest expense |  |  |  |  |  |  |  |  | (508,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | (515,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | (480,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Investment income (loss), net |  |  |  |  |  |  |  |  | 27,000,000 us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 17,000,000 us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 27,000,000 us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Equity in net income (losses) of investees, net |  |  |  |  |  |  |  |  | 46,000,000 us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | (93,000,000)us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 183,000,000 us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Other income (expense), net |  |  |  |  |  |  |  |  | (218,000,000)us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | (402,000,000)us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 917,000,000 us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Nonoperating income (expense) |  |  |  |  |  |  |  |  | (653,000,000)us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | (993,000,000)us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 647,000,000 us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Income before income taxes |  |  |  |  |  |  |  |  | 3,440,000,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 2,328,000,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 3,428,000,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Income tax expense |  |  |  |  |  |  |  |  | (143,000,000)us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | (206,000,000)us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | (197,000,000)us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Net income |  |  |  |  |  |  |  |  | 3,297,000,000 us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 2,122,000,000 us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | 3,231,000,000 us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember
Net income attributable to Parent |  |  |  |  |  |  |  |  | $ 3,115,000,000 us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | $ 1,968,000,000 us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember | $ 3,055,000,000 us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_NBCUniversalMediaLLCMember

X
- Definition Amount of net (income) loss attributable to noncontrolling interest and dividends on redeemable subsidiary preferred stock. + References No definition available. + Details
Name: | cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock
Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Other operating and administrative expense recognized in the period not presented separately. + References No definition available. + Details
Name: | cmcsa_OtherOperatingAndAdministrative
Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Programming and Production Costs + References No definition available. + Details
Name: | cmcsa_ProgrammingAndProductionCosts
Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
Name: | us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total costs of sales and operating expenses for the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_CostsAndExpenses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_CostsAndExpensesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 + Details
Name: | us-gaap_Depreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1252-109256 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 55 -Paragraph 52 -URI http://asc.fasb.org/extlink&oid=32703322&loc=d3e4984-109258 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.21) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.19) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.23) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 18 -Article 7 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 20 -Article 5 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 21 -Article 9 + Details
Name: | us-gaap_EarningsPerShareBasic
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1252-109256 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.21) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 18 -Article 7 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 20 -Article 5 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 21 -Article 9 + Details
Name: | us-gaap_EarningsPerShareDiluted
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 10 -Article 5 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 9 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=16385135&loc=d3e33749-111570 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.12) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 11 -Article 7 + Details
Name: | us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Article 4 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Income Tax Expense (or Benefit) -URI http://asc.fasb.org/extlink&oid=6515339 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319 + Details
Name: | us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of the cost of borrowed funds accounted for as interest expense. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.9) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 9 -Article 9 + Details
Name: | us-gaap_InterestExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate amount of income from investments (for example, dividends) not considered a component of the entity's core operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Article 5 + Details
Name: | us-gaap_InvestmentIncomeNonoperating
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The total expense recognized in the period for promotion, public relations, and brand or product advertising. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_MarketingAndAdvertisingExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 20 -Article 9 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Other Comprehensive Income -URI http://asc.fasb.org/extlink&oid=6519514 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Net Income -URI http://asc.fasb.org/extlink&oid=6518256 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.19) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.18) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.22) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e565-108580 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 19 -Article 5 + Details
Name: | us-gaap_NetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Article 5 + Details
Name: | us-gaap_NonoperatingIncomeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_NonoperatingIncomeExpenseAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The net result for the period of deducting operating expenses from operating revenues. + References No definition available. + Details
Name: | us-gaap_OperatingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The net amount of other income and expense amounts, the components of which are not separately disclosed on the income statement, resulting from ancillary business-related activities (that is, excluding major activities considered part of the normal operations of the business) also known as other nonoperating income (expense) recognized for the period. Such amounts may include: (a) dividends, (b) interest on securities, (c) net gains or losses on securities, (d) unusual costs, (e) gains or losses on foreign exchange transactions, and (f) miscellaneous other income and expense items. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 9 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.9) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_OtherNonoperatingIncomeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4K -URI http://asc.fasb.org/extlink&oid=31814832&loc=SL4591552-111686 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569616-111683 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4J -URI http://asc.fasb.org/extlink&oid=31814832&loc=SL4591551-111686 + Details
Name: | us-gaap_ProfitLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Article 5 + Details
Name: | us-gaap_Revenues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=cmcsa_NBCUniversalMediaLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |