v2.4.1.9

Condensed Consolidating Financial Information (Condensed Consolidating Statement of Income) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Service revenue	$ 17,853,000,000us-gaap_SalesRevenueServicesNet	$ 17,408,000,000us-gaap_SalesRevenueServicesNet
Management fee revenue	0us-gaap_ManagementFeesRevenue	0us-gaap_ManagementFeesRevenue
Revenue	17,853,000,000us-gaap_Revenues	17,408,000,000us-gaap_Revenues
Programming and production	5,463,000,000cmcsa_ProgrammingAndProductionCosts	5,908,000,000cmcsa_ProgrammingAndProductionCosts
Other operating and administrative	5,079,000,000cmcsa_OtherOperatingAndAdministrative	4,749,000,000cmcsa_OtherOperatingAndAdministrative
Advertising, marketing and promotion	1,355,000,000us-gaap_MarketingAndAdvertisingExpense	1,213,000,000us-gaap_MarketingAndAdvertisingExpense
Depreciation	1,634,000,000us-gaap_Depreciation	1,569,000,000us-gaap_Depreciation
Amortization	432,000,000us-gaap_AmortizationOfIntangibleAssets	401,000,000us-gaap_AmortizationOfIntangibleAssets
Costs and expenses, total	13,963,000,000us-gaap_CostsAndExpenses	13,840,000,000us-gaap_CostsAndExpenses
Operating income (loss)	3,890,000,000us-gaap_OperatingIncomeLoss	3,568,000,000us-gaap_OperatingIncomeLoss
Interest expense	(656,000,000)us-gaap_InterestExpense	(642,000,000)us-gaap_InterestExpense
Investment income (loss), net	33,000,000us-gaap_InvestmentIncomeNonoperating	113,000,000us-gaap_InvestmentIncomeNonoperating
Equity in net income (losses) of investees, net	33,000,000us-gaap_IncomeLossFromEquityMethodInvestments	32,000,000us-gaap_IncomeLossFromEquityMethodInvestments
Other income (expense), net	102,000,000us-gaap_OtherNonoperatingIncomeExpense	(15,000,000)us-gaap_OtherNonoperatingIncomeExpense
Nonoperating income (Expense), Total	(488,000,000)us-gaap_NonoperatingIncomeExpense	(512,000,000)us-gaap_NonoperatingIncomeExpense
Income (loss) before income taxes	3,402,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	3,056,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Income tax (expense) benefit	(1,261,000,000)us-gaap_IncomeTaxExpenseBenefit	(1,118,000,000)us-gaap_IncomeTaxExpenseBenefit
Net income (loss)	2,141,000,000us-gaap_ProfitLoss	1,938,000,000us-gaap_ProfitLoss
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	(82,000,000)cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock	(67,000,000)cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock
Net income (loss) attributable to Parent	2,059,000,000us-gaap_NetIncomeLoss	1,871,000,000us-gaap_NetIncomeLoss
Comprehensive income attributable to Parent	2,017,000,000us-gaap_ComprehensiveIncomeNetOfTax	1,848,000,000us-gaap_ComprehensiveIncomeNetOfTax
Elimination and Consolidation Adjustments [Member]
Service revenue	0us-gaap_SalesRevenueServicesNet / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_SalesRevenueServicesNet / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Management fee revenue	(631,000,000)us-gaap_ManagementFeesRevenue / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(594,000,000)us-gaap_ManagementFeesRevenue / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Revenue	(631,000,000)us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(594,000,000)us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Programming and production	0cmcsa_ProgrammingAndProductionCosts / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0cmcsa_ProgrammingAndProductionCosts / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Other operating and administrative	(631,000,000)cmcsa_OtherOperatingAndAdministrative / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(594,000,000)cmcsa_OtherOperatingAndAdministrative / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Advertising, marketing and promotion	0us-gaap_MarketingAndAdvertisingExpense / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_MarketingAndAdvertisingExpense / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Depreciation	0us-gaap_Depreciation / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_Depreciation / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Amortization	0us-gaap_AmortizationOfIntangibleAssets / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_AmortizationOfIntangibleAssets / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Costs and expenses, total	(631,000,000)us-gaap_CostsAndExpenses / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(594,000,000)us-gaap_CostsAndExpenses / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Operating income (loss)	0us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Interest expense	0us-gaap_InterestExpense / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_InterestExpense / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Investment income (loss), net	0us-gaap_InvestmentIncomeNonoperating / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_InvestmentIncomeNonoperating / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Equity in net income (losses) of investees, net	(10,250,000,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(9,734,000,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Other income (expense), net	0us-gaap_OtherNonoperatingIncomeExpense / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_OtherNonoperatingIncomeExpense / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Nonoperating income (Expense), Total	(10,250,000,000)us-gaap_NonoperatingIncomeExpense / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(9,734,000,000)us-gaap_NonoperatingIncomeExpense / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Income (loss) before income taxes	(10,250,000,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(9,734,000,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Income tax (expense) benefit	0us-gaap_IncomeTaxExpenseBenefit / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0us-gaap_IncomeTaxExpenseBenefit / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Net income (loss)	(10,250,000,000)us-gaap_ProfitLoss / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(9,734,000,000)us-gaap_ProfitLoss / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Net income (loss) attributable to Parent	(10,250,000,000)us-gaap_NetIncomeLoss / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(9,734,000,000)us-gaap_NetIncomeLoss / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Comprehensive income attributable to Parent	(10,180,000,000)us-gaap_ComprehensiveIncomeNetOfTax / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember	(9,719,000,000)us-gaap_ComprehensiveIncomeNetOfTax / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Comcast Parent [Member]
Service revenue	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Management fee revenue	244,000,000us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	230,000,000us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Revenue	244,000,000us-gaap_Revenues / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	230,000,000us-gaap_Revenues / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Programming and production	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Other operating and administrative	226,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	93,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Advertising, marketing and promotion	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Depreciation	8,000,000us-gaap_Depreciation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	7,000,000us-gaap_Depreciation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Amortization	1,000,000us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	1,000,000us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Costs and expenses, total	235,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	101,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Operating income (loss)	9,000,000us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	129,000,000us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Interest expense	(410,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	(387,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Investment income (loss), net	1,000,000us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	1,000,000us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Equity in net income (losses) of investees, net	2,322,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	2,038,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Other income (expense), net	(5,000,000)us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	0us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Nonoperating income (Expense), Total	1,908,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	1,652,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Income (loss) before income taxes	1,917,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	1,781,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Income tax (expense) benefit	142,000,000us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	90,000,000us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Net income (loss)	2,059,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	1,871,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Net income (loss) attributable to Parent	2,059,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	1,871,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Comprehensive income attributable to Parent	2,017,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = us-gaap_ParentCompanyMember	1,848,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Comcast Holdings [Member]
Service revenue	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Management fee revenue	0us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Revenue	0us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Programming and production	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Other operating and administrative	0cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Advertising, marketing and promotion	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Depreciation	0us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Amortization	0us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Costs and expenses, total	0us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Operating income (loss)	0us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Interest expense	(3,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	(3,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Investment income (loss), net	2,000,000us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	3,000,000us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Equity in net income (losses) of investees, net	2,226,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	2,267,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Other income (expense), net	0us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Nonoperating income (Expense), Total	2,225,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	2,267,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Income (loss) before income taxes	2,225,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	2,267,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Income tax (expense) benefit	0us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Net income (loss)	2,225,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	2,267,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Net income (loss) attributable to Parent	2,225,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	2,267,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Comprehensive income attributable to Parent	2,209,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember	2,269,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
CCCL Parent [Member]
Service revenue	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_CcclParentMember	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_CcclParentMember
Management fee revenue	237,000,000us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_CcclParentMember	223,000,000us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_CcclParentMember
Revenue	237,000,000us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_CcclParentMember	223,000,000us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_CcclParentMember
Programming and production	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_CcclParentMember	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_CcclParentMember
Other operating and administrative	237,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_CcclParentMember	223,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_CcclParentMember
Advertising, marketing and promotion	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_CcclParentMember	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_CcclParentMember
Depreciation	0us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_CcclParentMember	0us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_CcclParentMember
Amortization	0us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_CcclParentMember	0us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_CcclParentMember
Costs and expenses, total	237,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_CcclParentMember	223,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_CcclParentMember
Operating income (loss)	0us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_CcclParentMember	0us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_CcclParentMember
Interest expense	(44,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_CcclParentMember	(45,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_CcclParentMember
Investment income (loss), net	0us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_CcclParentMember	0us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_CcclParentMember
Equity in net income (losses) of investees, net	1,973,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_CcclParentMember	2,165,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_CcclParentMember
Other income (expense), net	0us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_CcclParentMember	0us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_CcclParentMember
Nonoperating income (Expense), Total	1,929,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_CcclParentMember	2,120,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_CcclParentMember
Income (loss) before income taxes	1,929,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_CcclParentMember	2,120,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_CcclParentMember
Income tax (expense) benefit	15,000,000us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_CcclParentMember	16,000,000us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_CcclParentMember
Net income (loss)	1,944,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_CcclParentMember	2,136,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_CcclParentMember
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_CcclParentMember	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_CcclParentMember
Net income (loss) attributable to Parent	1,944,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_CcclParentMember	2,136,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_CcclParentMember
Comprehensive income attributable to Parent	1,943,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_CcclParentMember	2,138,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_CcclParentMember
Combined CCHMO Parents [Member]
Service revenue	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Management fee revenue	150,000,000us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	141,000,000us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Revenue	150,000,000us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	141,000,000us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Programming and production	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Other operating and administrative	150,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	141,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Advertising, marketing and promotion	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Depreciation	0us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Amortization	0us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Costs and expenses, total	150,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	141,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Operating income (loss)	0us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Interest expense	(29,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	(29,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Investment income (loss), net	0us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Equity in net income (losses) of investees, net	1,646,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	1,511,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Other income (expense), net	0us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Nonoperating income (Expense), Total	1,617,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	1,482,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Income (loss) before income taxes	1,617,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	1,482,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Income tax (expense) benefit	10,000,000us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	10,000,000us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Net income (loss)	1,627,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	1,492,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Net income (loss) attributable to Parent	1,627,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	1,492,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Comprehensive income attributable to Parent	1,626,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember	1,493,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
NBCUniversal Media Parent [Member]
Service revenue	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	0us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Management fee revenue	0us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	0us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Revenue	0us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	0us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Programming and production	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	0cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Other operating and administrative	237,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	257,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Advertising, marketing and promotion	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	0us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Depreciation	0us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	0us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Amortization	0us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	0us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Costs and expenses, total	237,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	257,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Operating income (loss)	(237,000,000)us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	(257,000,000)us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Interest expense	(120,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	(124,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Investment income (loss), net	(6,000,000)us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	1,000,000us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Equity in net income (losses) of investees, net	1,231,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	1,071,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Other income (expense), net	(11,000,000)us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	(4,000,000)us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Nonoperating income (Expense), Total	1,094,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	944,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Income (loss) before income taxes	857,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	687,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Income tax (expense) benefit	(5,000,000)us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	(5,000,000)us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Net income (loss)	852,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	682,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	0cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Net income (loss) attributable to Parent	852,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	682,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Comprehensive income attributable to Parent	801,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember	685,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Comcast Non-Guarantor Subsidiaries [Member]
Service revenue	17,853,000,000us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	17,408,000,000us-gaap_SalesRevenueServicesNet / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Management fee revenue	0us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	0us-gaap_ManagementFeesRevenue / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Revenue	17,853,000,000us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	17,408,000,000us-gaap_Revenues / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Programming and production	5,463,000,000cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	5,908,000,000cmcsa_ProgrammingAndProductionCosts / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Other operating and administrative	4,860,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	4,629,000,000cmcsa_OtherOperatingAndAdministrative / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Advertising, marketing and promotion	1,355,000,000us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	1,213,000,000us-gaap_MarketingAndAdvertisingExpense / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Depreciation	1,626,000,000us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	1,562,000,000us-gaap_Depreciation / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Amortization	431,000,000us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	400,000,000us-gaap_AmortizationOfIntangibleAssets / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Costs and expenses, total	13,735,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	13,712,000,000us-gaap_CostsAndExpenses / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Operating income (loss)	4,118,000,000us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	3,696,000,000us-gaap_OperatingIncomeLoss / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Interest expense	(50,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	(54,000,000)us-gaap_InterestExpense / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Investment income (loss), net	36,000,000us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	108,000,000us-gaap_InvestmentIncomeNonoperating / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Equity in net income (losses) of investees, net	885,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	714,000,000us-gaap_IncomeLossFromEquityMethodInvestments / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Other income (expense), net	118,000,000us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	(11,000,000)us-gaap_OtherNonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Nonoperating income (Expense), Total	989,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	757,000,000us-gaap_NonoperatingIncomeExpense / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Income (loss) before income taxes	5,107,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	4,453,000,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Income tax (expense) benefit	(1,423,000,000)us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	(1,229,000,000)us-gaap_IncomeTaxExpenseBenefit / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Net income (loss)	3,684,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	3,224,000,000us-gaap_ProfitLoss / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	(82,000,000)cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	(67,000,000)cmcsa_NetIncomeLossAttributableToNoncontrollingInterestsAndRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Net income (loss) attributable to Parent	3,602,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	3,157,000,000us-gaap_NetIncomeLoss / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Comprehensive income attributable to Parent	$ 3,601,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember	$ 3,134,000,000us-gaap_ComprehensiveIncomeNetOfTax / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember

X

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Amount of net (income) loss attributable to noncontrolling interest and dividends on redeemable subsidiary preferred stock.

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Other operating and administrative expense recognized in the period not presented separately.

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Programming and Production Costs

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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.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Total costs of sales and operating expenses for the period.

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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.

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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.

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Amount of the cost of borrowed funds accounted for as interest expense.

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