0.750% Notes due 2032 Notes 0.750 percent due 2032 [Member] Notes 0.750% due 2032 [Member] In production and in development Film, Monetized On Its Own, Capitalized Cost, In Production And In Development Amounts of capitalized film cost incurred in production and in development of film predominantly monetized on its own Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Repurchases and repayments of debt Repayments of Long-Term Debt Media, Studios, Theme Parks headquarters and other Media, Studios, Theme Parks Segments Headquarters And Other [Member] Media, Studios, Theme Parks Segments Headquarters And Other Marketing and promotion Marketing and Advertising Expense 1.875% Notes due 2036 Notes 1.875 percent due 2036 [Member] Notes 1.875% due 2036 [Member] Cover [Abstract] Cover [Abstract] Increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Currency translation adjustments, net of deferred taxes Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Residential Connectivity Residential Connectivity [Member] Residential Connectivity [Member] Segments [Axis] Segments [Axis] Trading Symbol Trading Symbol Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Long-term debt, gross Long-Term Debt, Gross Noncurrent portion of debt Long-Term Debt and Lease Obligation Schedule of Weighted Average Common Shares Outstanding Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Supplemental Financial Information Additional Financial Information Disclosure [Text Block] External Customers External Customers [Member] External Customers Schedule of Other Balance Sheet Accounts Schedule Of Other Balance Sheet Accounts Related To Recognition Of Revenue [Table Text Block] Schedule Of Other Balance Sheet Accounts [Table Text Block] Cash dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Declared Income taxes Income Taxes Paid, Net Domestic broadband Domestic Broadband [Member] Domestic Broadband Costs and Expenses: Costs and Expenses [Abstract] Less: Allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Class A Common Stock, $0.01 par value Class A Common Stock Common Class A [Member] Contributions from (distributions to) noncontrolling interests, net Contributions From And Distributions To Noncontrolling Interests Attributable To Temporary Equity Contributions from and (distributions to) noncontrolling interests attributable to temporary equity. Deferred gains (losses), net of deferred taxes of $3, $(19), $1, and $4 Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Weighted-average fair value of restricted share units granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Equity method Equity Method Investments Redeemable noncontrolling interests Balance, beginning of period Balance, end of period Redeemable Noncontrolling Interest, Equity, Carrying Amount Line of Credit Facility [Table] Line of Credit Facility [Table] Total investments Investments Investments Noncurrent investments Long-Term Investments Segments [Domain] Segments [Domain] Realized and unrealized gains (losses) on equity securities, net Equity Securities, FV-NI, Gain (Loss) 1.250% Notes due 2040 Notes 1.250 percent due 2040 [Member] Notes 1.250% due 2040 [Member] Theatrical Theatrical [Member] Theatrical [Member] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Universal Beijing Resort Term Loans Universal Beijing Resort Term Loans [Member] Universal Beijing Resort Term Loans [Member] Unbilled Revenues Unbilled Revenues [Member] 1.500% Notes due 2029 Notes 1.500 percent Due 2029 [Member] Notes 1.500% Due 2029 [Member] Domestic distribution Domestic Distribution [Member] Domestic Distribution Notes Receivable Notes Receivable [Member] Programming and production Total programming and production costs Programming And Production Costs The amount of expense recognized in the period for costs associated with video programming and content acquisition and production costs. Programming expenses include the fees paid to license the programming distributed to video customers, such as the programming license fees charged by cable networks and fees charged for retransmission of the signals from local broadcast television stations. Production costs include the amortization of owned and acquired programming, sports rights, direct production costs, residual and participation payments, production overhead, costs associated with the distribution of programming to third-party networks and other distribution platforms, and on-air talent costs. It also includes the amortization of capitalized theatrical film production and acquisition costs and distribution expenses. Other operating assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Investment, Name [Domain] Investment, Name [Domain] 3.250% Notes due 2032 Notes 3.250 percent due 2032 [Member] Notes 3.250 percent due 2032 Common stock, shares outstanding at end of period (in shares) Common Stock, Shares, Outstanding Total fair value of debt Debt Instrument, Fair Value Disclosure Billing Status, Type [Axis] Billing Status, Type [Axis] Other investments Other Investments Other income (loss), net Other Nonoperating Income (Expense) Total carrying value of debt Debt and Lease Obligation Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Revenue from Contract with Customer [Abstract] Plan Name [Domain] Plan Name [Domain] Equity in net income (losses) of investees, net Income (Loss) from Equity Method Investments Treasury stock, 872,791,028 Class A common shares Treasury Stock, Common, Value Other noncurrent assets, net Other Assets, Noncurrent Entity Tax Identification Number Entity Tax Identification Number Content licensing Content Licensing [Member] Content Licensing [Member] Operating Segments Operating Segments [Member] Dividends payable Dividends Payable Receivable Type [Axis] Receivable Type [Axis] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Treasury Stock at Cost Treasury Stock, Common [Member] Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Theme Parks Theme Parks Segment [Member] Theme Parks Member Plan Name [Axis] Plan Name [Axis] 3.550% Notes due 2036 Notes 3.550 percent due 2036 [Member] Notes 3.550 percent due 2036 Other Stockholders' Equity, Other Equity Components [Axis] Equity Components [Axis] 5.250% Notes due 2040 Notes 5.250 percent due 2040 [Member] Notes 5.250 percent due 2040 Other current assets Other Assets, Current Local Phone Number Local Phone Number Finance Receivable Program [Axis] Finance Receivable Program [Axis] Finance Receivable Program Released, less amortization Film, Monetized on Its Own, Capitalized Cost, Released Equipment Installment Plan Equipment Installment Plan [Member] Equipment Installment Plan Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Deferred income taxes Deferred Income Tax Liabilities, Net Schedule of Equity Method Investments [Table] Equity Method Investment [Table] Total costs and expenses Costs and Expenses Other Industries [Abstract] Other Industries [Abstract] Receivable [Domain] Receivable [Domain] Changes in operating assets and liabilities, net of effects of acquisitions and divestitures: Increase (Decrease) in Operating Capital [Abstract] Entity Small Business Entity Small Business Employee benefit obligations and other, net of deferred taxes of $2, $2, $10 and $5 Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Other Other [Member] Other [Member] Equity method investments and certain retained distributions Equity Method Investments and Certain Retained Distributions Equity Method Investments and Certain Retained Distributions Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Film and television costs, net Increase (Decrease) In Film And Television Costs Net Increase (Decrease) In Film And Television Costs Net Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Noncash interest expense (income), net Noncash Interest Expense (Income) Net Represents noncash interest expense (income) items as adjustments to reconcile net income (loss) to cash provided by (used in) operating activities. Debt Disclosure [Abstract] Debt Disclosure [Abstract] Common Stock Common Stock [Member] Accrued expenses and other current liabilities Accrued Liabilities, Current Construction of Universal Beijing Resort Payments For Construction Of Theme Park The cash outflow associated with the construction of a theme park. Antidilutive securities Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Issuances of common stock under employee plans Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Investments [Abstract] Investments [Abstract] Revolving Credit Facility Due May 17, 2029 Revolving Credit Facility Due May 17, 2029 [Member] Revolving Credit Facility Due May 17, 2029 Preferred stock, authorized (in shares) Preferred Stock, Shares Authorized Completed, not released Film, Monetized on Its Own, Capitalized Cost, Completed and Not Released Line of Credit Line of Credit [Member] Residential Connectivity & Platforms Residential Connectivity And Platforms Segment [Member] Residential Connectivity And Platforms Segment Entity Emerging Growth Company Entity Emerging Growth Company Atairos Atairos [Member] Atairos [Member] Finance Receivable Program [Domain] Finance Receivable Program [Domain] Finance Receivable Program [Domain] Media Media Segment [Member] Media Segment Credit Facility [Domain] Credit Facility [Domain] Cash, cash equivalents and restricted cash, beginning of period Cash, cash equivalents and restricted cash, end of period Cash, cash equivalents and restricted cash, end of period Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Short-Term Instruments Short-Term Instruments [Member] Short-Term Instruments Film and television costs Film, Monetized On Its Own Capitalized Cost, And Entertainment, License Agreement For Program Material, Including Sports Rights Advances Total amounts of capitalized film cost for film predominantly monetized on its own and capitalized cost for rights acquired by broadcaster under license agreement for program material, including sports rights advances. Segment Reporting [Abstract] Segment Reporting [Abstract] Other Investments Other Investments [Member] Entity Central Index Key Entity Central Index Key International networks International Networks [Member] International Networks Cash flow hedges: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Unrecognized pretax compensation expense on nonvested awards Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Owned: Film, Capitalized Cost [Abstract] Franchise rights Indefinite-Lived Franchise Rights Current Assets: Assets, Current [Abstract] Goodwill Goodwill Corporate and Other Corporate And Other, Type [Member] Corporate And Other, Type Contributions from (distributions to) noncontrolling interests, net Contributions From (Distributions To) Noncontrolling Interests Contributions From (Distributions To) Noncontrolling Interests Consolidation Items [Axis] Consolidation Items [Axis] Cumulative translation adjustments Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Advertising Advertising [Member] Management Grant Management Grant [Member] Management Grant [Member] Equity and Share-Based Compensation Equity [Text Block] Treasury (in shares) Treasury Stock, Common, Shares Accounts payable and accrued expenses related to trade creditors Increase (Decrease) in Accounts Payable and Accrued Liabilities Cash capital contributions for equity method investments Capital Contribution To VIE The cash outflow associated with a capital contribution to a VIE accounted for as an equity method investment Equity Component [Domain] Equity Component [Domain] Financial Instrument [Axis] Financial Instrument [Axis] Segment Information Segment Reporting Disclosure [Text Block] Product and Service [Domain] Product and Service [Domain] Depreciation Depreciation Depreciation Other Proceeds from (Payments for) Other Financing Activities Share-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Entity Shell Company Entity Shell Company Comprehensive income attributable to Comcast Corporation Comprehensive Income (Loss), Net of Tax, Attributable to Parent Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Domestic advertising Domestic Advertising [Member] Domestic Advertising Class B Common Stock Common Class B [Member] Advance on sale of investment Advance On Sale Of Investment Advance On Sale Of Investment Security Exchange Name Security Exchange Name Spread on variable rate Debt Instrument, Basis Spread on Variable Rate Consolidated Entities [Axis] Consolidated Entities [Axis] Statement [Table] Statement [Table] Award Type [Axis] Award Type [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Less: Other comprehensive income (loss) attributable to noncontrolling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest City Area Code City Area Code Current Liabilities: Liabilities, Current [Abstract] Property and equipment, net of accumulated depreciation of $60,114 and $58,701 Property, Plant and Equipment, Net Consolidated variable interest entity's liabilities included in condensed consolidated balance sheet Liabilities Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Noncontrolling interests Equity, Attributable to Noncontrolling Interest Schedule of Cash and Cash Equivalents Schedule of Cash and Cash Equivalents [Table Text Block] Purchase of short-term instruments Payments to Acquire Short-Term Investments Currency translation adjustments, net of deferred taxes of $(31), $(20), $(74) and $(42) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Total current assets Assets, Current Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Revolving Credit Facility Revolving Credit Facility [Member] Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Remaining borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Repurchases of common stock under repurchase program and employee plans Payments for Repurchase of Common Stock Common stock, issued (in shares) Common Stock, Shares, Issued Document And Entity Information [Line Items] Document Information [Line Items] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Weighted-average fair value of stock options granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Nonmarketable equity securities Equity Securities without Readily Determinable Fair Value, Amount Investments and Variable Interest Entities Investment [Text Block] Repurchases of common stock under repurchase program and employee plans Stock Repurchased and Retired During Period, Value Other operating and administrative Other Operating And Administrative Other operating and administrative expense recognized in the period not presented separately. Equity [Abstract] Retained earnings Retained Earnings (Accumulated Deficit) Property and equipment - accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total Accounts Receivable, after Allowance for Credit Loss Class of Stock [Domain] Class of Stock [Domain] Common stock, authorized (in shares) Common Stock, Shares Authorized Unrealized gains (losses) recognized Equity Securities, FV-NI, Unrealized Gain (Loss) Eliminations Consolidation, Eliminations [Member] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Net (gain) loss on investment activity and other (Gain) Loss On Investments And Other Noncash (Income) Loss, Net Net (gain) loss on investment activity, including cash received from investees, and other noncash income (loss), net. Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Weighted-average number of common shares outstanding – diluted Weighted Average Number of Shares Outstanding, Diluted Proceeds from (repayments of) short-term borrowings, net Proceeds from (Repayments of) Short-Term Debt 2.0% Exchangeable Subordinated Debentures due 2029 Exchangeable Subordinated Debentures 2.0 Percent Due 2029 [Member] Exchangeable Subordinated Debentures 2.0% Due 2029 [Member] Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Current and noncurrent receivables, net Increase (Decrease) In Current And Noncurrent Receivables Net The increase (decrease) during the reporting period in the amount of current and noncurrent receivables. 0.250% Notes due 2029 Notes 0.250 percent Due 2029 [Member] Notes 0.250 percent Due 2029 Owned Film, Monetized On Its Own, Amortization Expense, Including Participations And Residuals Amount of amortization expense for capitalized film cost for film predominantly monetized on its own and participation and residuals expenses. Deferred revenue Deferred Revenue, Current Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Credit Facility [Axis] Credit Facility [Axis] Owned Film, Monetized on Its Own, Capitalized Cost Total Comcast Corporation shareholders’ equity Equity, Attributable to Parent Dividends declared Dividends, Common Stock, Cash Schedule of Cash Payments for Interest and Income Taxes Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Amendment Flag Amendment Flag Entity Registrant Name Entity Registrant Name Universal Beijing Resort Universal Beijing Resort [Member] Universal Beijing Resort [Member] Depreciation and amortization Depreciation, Depletion and Amortization Redeemable Noncontrolling Interests Increase (Decrease) in Temporary Equity [Roll Forward] Interest expense Interest Expense, Nonoperating Deferred income taxes Deferred Income Tax Expense (Benefit) Schedule of Restricted Cash Restrictions on Cash and Cash Equivalents [Table Text Block] Proceeds from short-term instruments Proceeds from Sale of Short-Term Investments Remaining unfunded capital commitment Variable Interest Entity, Reporting Entity Involvement, Unfunded Capital Commitment Variable Interest Entity, Reporting Entity Involvement, Unfunded Capital Commitment Debt Debt Disclosure [Text Block] Current portion of debt Debt, Current Equity: Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Receivables, net Receivables, net Accounts Receivable, after Allowance for Credit Loss, Current Number of stock options granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Ownership percentage in variable interest entity Subsidiary, Ownership Percentage, Parent Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Deferred gains (losses) on cash flow hedges, deferred taxes Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Document Fiscal Period Focus Document Fiscal Period Focus 5.50% Notes due 2029 Notes 5.50 Percent Due 2029 [Member] Notes 5.50% Due 2029 [Member] Effect of dilutive securities Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Title of 12(b) Security Title of 12(b) Security Receivables, gross Accounts Receivable, before Allowance for Credit Loss, Current Common stock Common Stock, Value, Issued Proceeds from sales of businesses and investments Proceeds From Sales Of Businesses And Investments The cash inflow associated with the sale of businesses and investments, if any, during the period. Assets Assets [Abstract] Other comprehensive income (loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Schedule of Programming and Production Expense Schedule Of Programming And Production Cost [Table Text Block] Schedule Of Programming And Production Cost Document Type Document Type Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Schedule of Financial Data by Business Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Other Payments for (Proceeds from) Other Investing Activities Employee benefit obligations and other, deferred taxes Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Film and television content: Film And Television Content [Abstract] Film And Television Content Noncurrent receivables, net (included in other noncurrent assets, net) Accounts Receivable, after Allowance for Credit Loss, Noncurrent Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Preferred stock—authorized, 20,000,000 shares; issued, zero Preferred Stock, Value, Issued 0.000% Notes due 2026 Notes 0.000 percent Due 2026 [Member] Notes 0.000 percent Due 2026 Dividends payable (in dollars per share) Dividends Payable, Amount Per Share Variable Interest Entity, Not Primary Beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] Amortization Amortization Amortization of Intangible Assets Basic earnings (loss) per common share attributable to Comcast Corporation shareholders (in dollars per share) Earnings Per Share, Basic Receivables Billing Status [Domain] Receivables Billing Status [Domain] Accounts payable and accrued expenses related to trade creditors Accounts Payable, Current Revenues [Abstract] Revenues [Abstract] Domestic wireless Domestic Wireless [Member] Domestic Wireless Film and television costs Film, Monetized On Its Own, And Entertainment, License Agreement For Program Material, Including Sports Rights Advances, Capitalized Costs, Noncurrent Amount of capitalized film cost for film predominantly monetized on its own and capitalized cost for rights acquired by broadcaster under license agreement for program material, including sports rights advances, noncurrent. Net income (loss) Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Ownership [Domain] Ownership [Domain] Current Fiscal Year End Date Current Fiscal Year End Date Property and equipment and intangible assets accrued but not yet paid Capital Expenditures Incurred but Not yet Paid Less: Current investments Short-Term Investments Income before income taxes Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Amortization of owned film and television costs Film, Monetized on Its Own, Amortization Expense Total current liabilities Liabilities, Current Award Type [Domain] Award Type [Domain] Total assets Assets Assets Cash distribution received from equity method investments Proceeds from Equity Method Investment, Distribution Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Number of restricted share units granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Realized (gains) losses on cash flow hedges, deferred taxes Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Capital expenditures Payments to Acquire Property, Plant, and Equipment Other noncurrent liabilities Other Liabilities, Noncurrent Other Other Programming And Production Expense Other Programming And Production Expense Commitments and contingencies Commitments and Contingencies Licensed, including sports rights Entertainment, License Agreement For Program Material, Including Sports Rights Advances, Amortization Expense Amount of amortization expense for rights acquired by broadcaster under license agreement for program material, including sports rights advances. Schedule of Investment and Other Income (Loss), Net Components Of Investment And Other Income (Loss), Net [Table Text Block] Tabular disclosure of investment and other income (loss), net, including, but not limited to, equity in net income (losses) of investees, net, realized and unrealized gains (losses) on equity securities, net, and other income (loss), net. Additional Paid-In Capital Additional Paid-in Capital [Member] Schedule of Receivables, Net Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Investment, Name [Axis] Investment, Name [Axis] Condensed Consolidated Financial Statements Business Description and Basis of Presentation [Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Diluted earnings (loss) per common share attributable to Comcast Corporation shareholders (in dollars per share) Earnings Per Share, Diluted Class of Stock [Axis] Class of Stock [Axis] Corporate Type [Domain] Corporate Type [Domain] Corporate Type [Domain] Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Entity Interactive Data Current Entity Interactive Data Current Entity Address, City or Town Entity Address, City or Town Proceeds from borrowings Proceeds from Issuance of Long-Term Debt Ownership [Axis] Ownership [Axis] Debt Instrument [Axis] Debt Instrument [Axis] Recognized share-based compensation expense Share-Based Payment Arrangement, Expense Preferred stock, issued (in shares) Preferred Stock, Shares Issued Net income attributable to Comcast Corporation Net income Net Income (Loss) Attributable to Parent Customer [Axis] Customer [Axis] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Current borrowing capacity Line of Credit Facility, Current Borrowing Capacity Share-based compensation Share-Based Payment Arrangement, Noncash Expense Net income Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Entity File Number Entity File Number Unrecognized gains (losses) on employee benefit obligations and other Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Payment for purchases of transferable tax credits Payment For Purchases Of Transferable Tax Credits Payment For Purchases Of Transferable Tax Credits Income tax expense Income Tax Expense (Benefit) Consolidated Entities [Domain] Consolidated Entities [Domain] Revenue Revenue from Contract with Customer [Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Noncontrolling Interests Noncontrolling Interest [Member] Income Statement [Abstract] Income Statement [Abstract] Entity Address, Address Line One Entity Address, Address Line One Other comprehensive income (loss), net of tax (expense) benefit: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract] Other revenue Headquarters/Corporate and Other Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Other Temporary Equity, Other Changes Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Impact of foreign currency on cash, cash equivalents and restricted cash Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations Marketable equity securities Equity Securities, FV-NI Schedule of Capitalized Film and Television Costs Schedule Of Capitalized Film And Television Costs [Table Text Block] Schedule of capitalized costs for film predominantly monetized on its own and for rights acquired by broadcaster under license agreement for program material, including sports rights advances, recorded at the balance sheet date. Document Period End Date Document Period End Date Noncurrent deferred revenue (included in other noncurrent liabilities) Deferred Revenue, Noncurrent Revenue Revenue from Contract with Customer, Excluding Assessed Tax Cash paid for intangible assets Payments to Acquire Intangible Assets Investment and other income (loss), net Investment and other income (loss), net Nonoperating Income (Expense) Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Programming and Production Costs Entertainment [Text Block] Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Operating income Operating Income (Loss) Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] 0.250% Notes due 2027 Notes 0.250 percent Due 2027 [Member] Notes 0.250% Due 2027 [Member] Number of reportable segments Number of Reportable Segments Total liabilities and equity Liabilities and Equity Business Services Connectivity Business Services Connectivity Segment [Member] Business Services Connectivity Segment Additional paid-in capital Additional Paid in Capital Licensed, including sports advances Entertainment, License Agreement For Program Material, Including Sports Rights Advances, Capitalized Cost Amount of capitalized cost for rights acquired by broadcaster under license agreement for program material, including sports rights advances. Other intangible assets, net of accumulated amortization of $34,162 and $30,290 Other Intangible Assets, Net International connectivity International Connectivity [Member] International Connectivity Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Studios Studios Segment [Member] Studios Segment Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Less: Net income (loss) attributable to noncontrolling interests Less: Net income (loss) attributable to noncontrolling interests Net income (loss) Net Income (Loss) Attributable to Noncontrolling Interest Video Video [Member] Video Dividends paid Payments of Dividends Document Transition Report Document Transition Report Document Quarterly Report Document Quarterly Report Realized (gains) losses reclassified to net income, net of deferred taxes of $11, $2, $11 and $18 Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Adjusted EBITDA Adjusted EBITDA The measure used to evaluate the profitability of operating segments. Customer [Domain] Customer [Domain] Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Current Reporting Status Entity Current Reporting Status Retained Earnings Retained Earnings [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Accrued participations and residuals Accrued Participation Liabilities, Due in Next Operating Cycle Video distribution programming Video Distribution Programming Expense Video Distribution Programming Expense Restricted cash included in other current assets and other noncurrent assets, net Restricted Cash Deferred gains (losses) on cash flow hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Weighted-average number of common shares outstanding – basic Weighted Average Number of Shares Outstanding, Basic Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Product and Service [Axis] Product and Service [Axis] Corporate Type [Axis] Corporate Type [Axis] Corporate Type Entity Address, State or Province Entity Address, State or Province Statement [Line Items] Statement [Line Items] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Intersegment Customers Intersegment Customers [Member] Intersegment Customers Document And Entity Information [Table] Document Information [Table] Schedule of Investment Summary Summary Investment Holdings [Table Text Block] Total equity Balance, beginning of period Balance, end of period Accumulated other comprehensive income (loss), net of deferred taxes Equity, Including Portion Attributable to Noncontrolling Interest Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Purchases of investments Payments to Acquire Investments Financial Instruments [Domain] Financial Instruments [Domain] Liabilities and Equity Liabilities and Equity [Abstract] Entity Filer Category Entity Filer Category