v2.4.1.9

Condensed Consolidating Financial Information (Condensed Consolidating Statement of Cash Flows) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended
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Mar. 31, 2015 | Mar. 31, 2014
Operating Activities |  |
Net cash provided by (used in) operating activities | $ 5,245 us-gaap_NetCashProvidedByUsedInOperatingActivities | $ 4,486 us-gaap_NetCashProvidedByUsedInOperatingActivities
Investing Activities |  |
Net transactions with affiliates | 0 cmcsa_NetTransactionsWithAffiliates | 0 cmcsa_NetTransactionsWithAffiliates
Capital expenditures | (1,726)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment | (1,448)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Cash paid for intangible assets | (273)us-gaap_PaymentsToAcquireIntangibleAssets | (217)us-gaap_PaymentsToAcquireIntangibleAssets
Acquisitions and construction of real estate properties | (24)cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties
Proceeds from sales of businesses and investments | 180 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments | 300 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments
Purchases of investments | (32)us-gaap_PaymentsToAcquireInvestments | (37)us-gaap_PaymentsToAcquireInvestments
Other | 181 us-gaap_PaymentsForProceedsFromOtherInvestingActivities | (103)us-gaap_PaymentsForProceedsFromOtherInvestingActivities
Net cash provided by (used in) investing activities | (1,694)us-gaap_NetCashProvidedByUsedInInvestingActivities | (1,505)us-gaap_NetCashProvidedByUsedInInvestingActivities
Financing Activities |  |
Proceeds from (repayments of) short-term borrowings, net | (150)us-gaap_ProceedsFromRepaymentsOfShortTermDebt | (364)us-gaap_ProceedsFromRepaymentsOfShortTermDebt
Proceeds from borrowings | 0 us-gaap_ProceedsFromOtherDebt | 2,187 us-gaap_ProceedsFromOtherDebt
Repurchases and repayments of debt | (909)us-gaap_RepaymentsOfOtherDebt | (2,260)us-gaap_RepaymentsOfOtherDebt
Repurchases and retirements of common stock | (2,000)us-gaap_PaymentsForRepurchaseOfCommonStock | (750)us-gaap_PaymentsForRepurchaseOfCommonStock
Dividends paid | (572)us-gaap_PaymentsOfDividends | (508)us-gaap_PaymentsOfDividends
Issuances of common stock | 28 us-gaap_ProceedsFromIssuanceOfCommonStock | 20 us-gaap_ProceedsFromIssuanceOfCommonStock
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock | (62)cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock | (66)cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock
Other | 141 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities | 96 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities
Net cash provided by (used in) financing activities | (3,524)us-gaap_NetCashProvidedByUsedInFinancingActivities | (1,645)us-gaap_NetCashProvidedByUsedInFinancingActivities
Increase (decrease) in cash and cash equivalents | 27 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease | 1,336 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Cash and cash equivalents, beginning of period | 3,910 us-gaap_CashAndCashEquivalentsAtCarryingValue | 1,718 us-gaap_CashAndCashEquivalentsAtCarryingValue
Cash and cash equivalents, end of period | 3,937 us-gaap_CashAndCashEquivalentsAtCarryingValue | 3,054 us-gaap_CashAndCashEquivalentsAtCarryingValue
Elimination and Consolidation Adjustments [Member] |  |
Operating Activities |  |
Net cash provided by (used in) operating activities | 0 us-gaap_NetCashProvidedByUsedInOperatingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_NetCashProvidedByUsedInOperatingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Investing Activities |  |
Net transactions with affiliates | 0 cmcsa_NetTransactionsWithAffiliates / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 cmcsa_NetTransactionsWithAffiliates / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Capital expenditures | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Cash paid for intangible assets | 0 us-gaap_PaymentsToAcquireIntangibleAssets / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_PaymentsToAcquireIntangibleAssets / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Acquisitions and construction of real estate properties | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Proceeds from sales of businesses and investments | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Purchases of investments | 0 us-gaap_PaymentsToAcquireInvestments / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_PaymentsToAcquireInvestments / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Other | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Net cash provided by (used in) investing activities | 0 us-gaap_NetCashProvidedByUsedInInvestingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_NetCashProvidedByUsedInInvestingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Financing Activities |  |
Proceeds from (repayments of) short-term borrowings, net | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Proceeds from borrowings | 0 us-gaap_ProceedsFromOtherDebt / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_ProceedsFromOtherDebt / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Repurchases and repayments of debt | 0 us-gaap_RepaymentsOfOtherDebt / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_RepaymentsOfOtherDebt / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Repurchases and retirements of common stock | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Dividends paid | 0 us-gaap_PaymentsOfDividends / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_PaymentsOfDividends / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Issuances of common stock | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Other | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Net cash provided by (used in) financing activities | 0 us-gaap_NetCashProvidedByUsedInFinancingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_NetCashProvidedByUsedInFinancingActivities / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Increase (decrease) in cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Cash and cash equivalents, beginning of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Cash and cash equivalents, end of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_ConsolidationItemsAxis = cmcsa_EliminationAndConsolidationAdjustmentsMember
Comcast Parent [Member] |  |
Operating Activities |  |
Net cash provided by (used in) operating activities | (294)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (96)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Investing Activities |  |
Net transactions with affiliates | 3,609 cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 1,370 cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Capital expenditures | (6)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Cash paid for intangible assets | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Acquisitions and construction of real estate properties | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Proceeds from sales of businesses and investments | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Purchases of investments | 0 us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (10)us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Other | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Net cash provided by (used in) investing activities | 3,603 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 1,360 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Financing Activities |  |
Proceeds from (repayments of) short-term borrowings, net | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (1,350)us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Proceeds from borrowings | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 2,184 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Repurchases and repayments of debt | (900)us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (1,000)us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Repurchases and retirements of common stock | (2,000)us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (750)us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Dividends paid | (572)us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (508)us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Issuances of common stock | 28 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 20 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Other | 135 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 140 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Net cash provided by (used in) financing activities | (3,309)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (1,264)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Increase (decrease) in cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Cash and cash equivalents, beginning of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Cash and cash equivalents, end of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Comcast Holdings [Member] |  |
Operating Activities |  |
Net cash provided by (used in) operating activities | (1)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | (2)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Investing Activities |  |
Net transactions with affiliates | 1 cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 2 cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Capital expenditures | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Cash paid for intangible assets | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Acquisitions and construction of real estate properties | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Proceeds from sales of businesses and investments | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Purchases of investments | 0 us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Other | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Net cash provided by (used in) investing activities | 1 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 2 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Financing Activities |  |
Proceeds from (repayments of) short-term borrowings, net | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Proceeds from borrowings | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Repurchases and repayments of debt | 0 us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Repurchases and retirements of common stock | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Dividends paid | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Issuances of common stock | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Other | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Net cash provided by (used in) financing activities | 0 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Increase (decrease) in cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Cash and cash equivalents, beginning of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
Cash and cash equivalents, end of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_ComcastHoldingsMember
CCCL Parent [Member] |  |
Operating Activities |  |
Net cash provided by (used in) operating activities | 82 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember | 110 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember
Investing Activities |  |
Net transactions with affiliates | (82)cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_CcclParentMember | (110)cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_CcclParentMember
Capital expenditures | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_CcclParentMember
Cash paid for intangible assets | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_CcclParentMember
Acquisitions and construction of real estate properties | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_CcclParentMember
Proceeds from sales of businesses and investments | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_CcclParentMember
Purchases of investments | 0 us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_CcclParentMember
Other | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember
Net cash provided by (used in) investing activities | (82)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember | (110)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember
Financing Activities |  |
Proceeds from (repayments of) short-term borrowings, net | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_CcclParentMember
Proceeds from borrowings | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_CcclParentMember
Repurchases and repayments of debt | 0 us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_CcclParentMember
Repurchases and retirements of common stock | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_CcclParentMember
Dividends paid | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_CcclParentMember
Issuances of common stock | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_CcclParentMember
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_CcclParentMember
Other | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember
Net cash provided by (used in) financing activities | 0 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_CcclParentMember
Increase (decrease) in cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_CcclParentMember
Cash and cash equivalents, beginning of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_CcclParentMember
Cash and cash equivalents, end of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_CcclParentMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_CcclParentMember
Combined CCHMO Parents [Member] |  |
Operating Activities |  |
Net cash provided by (used in) operating activities | (48)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | (47)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Investing Activities |  |
Net transactions with affiliates | 48 cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 47 cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Capital expenditures | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Cash paid for intangible assets | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Acquisitions and construction of real estate properties | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Proceeds from sales of businesses and investments | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Purchases of investments | 0 us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Other | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Net cash provided by (used in) investing activities | 48 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 47 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Financing Activities |  |
Proceeds from (repayments of) short-term borrowings, net | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Proceeds from borrowings | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Repurchases and repayments of debt | 0 us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Repurchases and retirements of common stock | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Dividends paid | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Issuances of common stock | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Other | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Net cash provided by (used in) financing activities | 0 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Increase (decrease) in cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Cash and cash equivalents, beginning of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
Cash and cash equivalents, end of period | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_CombinedCchmoParentsMember
NBCUniversal Media Parent [Member] |  |
Operating Activities |  |
Net cash provided by (used in) operating activities | (361)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | (306)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Investing Activities |  |
Net transactions with affiliates | 321 cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 483 cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Capital expenditures | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Cash paid for intangible assets | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Acquisitions and construction of real estate properties | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Proceeds from sales of businesses and investments | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Purchases of investments | 0 us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | (6)us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Other | (5)us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Net cash provided by (used in) investing activities | 316 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 477 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Financing Activities |  |
Proceeds from (repayments of) short-term borrowings, net | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Proceeds from borrowings | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Repurchases and repayments of debt | (1)us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | (1)us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Repurchases and retirements of common stock | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Dividends paid | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Issuances of common stock | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Other | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 0 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Net cash provided by (used in) financing activities | (1)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | (1)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Increase (decrease) in cash and cash equivalents | (46)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 170 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Cash and cash equivalents, beginning of period | 385 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 336 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Cash and cash equivalents, end of period | 339 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember | 506 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_NbcuniversalMediaParentMember
Comcast Non-Guarantor Subsidiaries [Member] |  |
Operating Activities |  |
Net cash provided by (used in) operating activities | 5,867 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 4,827 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Investing Activities |  |
Net transactions with affiliates | (3,897)cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (1,792)cmcsa_NetTransactionsWithAffiliates / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Capital expenditures | (1,720)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (1,448)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Cash paid for intangible assets | (273)us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (217)us-gaap_PaymentsToAcquireIntangibleAssets / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Acquisitions and construction of real estate properties | (24)cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 0 cmcsa_PaymentsForAcquisitionsAndConstructionOfRealEstateProperties / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Proceeds from sales of businesses and investments | 180 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 300 cmcsa_ProceedsFromSalesOfBusinessesAndInvestments / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Purchases of investments | (32)us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (21)us-gaap_PaymentsToAcquireInvestments / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Other | 186 us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (103)us-gaap_PaymentsForProceedsFromOtherInvestingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Net cash provided by (used in) investing activities | (5,580)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (3,281)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Financing Activities |  |
Proceeds from (repayments of) short-term borrowings, net | (150)us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 986 us-gaap_ProceedsFromRepaymentsOfShortTermDebt / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Proceeds from borrowings | 0 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 3 us-gaap_ProceedsFromOtherDebt / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Repurchases and repayments of debt | (8)us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (1,259)us-gaap_RepaymentsOfOtherDebt / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Repurchases and retirements of common stock | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Dividends paid | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 0 us-gaap_PaymentsOfDividends / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Issuances of common stock | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 0 us-gaap_ProceedsFromIssuanceOfCommonStock / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock | (62)cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (66)cmcsa_DistributionsToNoncontrollingInterestsAndDividendsForRedeemableSubsidiaryPreferredStock / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Other | 6 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (44)us-gaap_ProceedsFromPaymentsForOtherFinancingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Net cash provided by (used in) financing activities | (214)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | (380)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Increase (decrease) in cash and cash equivalents | 73 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 1,166 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Cash and cash equivalents, beginning of period | 3,525 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | 1,382 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember
Cash and cash equivalents, end of period | $ 3,598 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember | $ 2,548 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cmcsa_ComcastNonGuarantorSubsidiariesMember

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- Definition Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders and dividends for redeemable subsidiary preferred stock. + References No definition available. + Details
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- Definition Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585 + Details
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- Definition The cash outflow associated with the purchase of all investments (debt, security, other) during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585 + Details
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