Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Income Statement [Table] Condensed Income Statement [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Elimination and Consolidation Adjustments [Member] Corporate Reconciling Items And Eliminations [Member] Represents the aggregate total of adjustments for non operating corporate items, reconciling items and eliminations. Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Comcast Parent [Member] Parent Company [Member] Comcast Holdings [Member] Comcast Holdings [Member] Comcast Holdings CCCL Parent [Member] CCCL Parent [Member] CCCL Parent NBCUniversal Media Parent [Member] NBCUniversal Media Parent [Member] Comcast Non-Guarantor Subsidiaries [Member] Comcast Non-Guarantor Subsidiaries [Member] Non-Guarantor Subsidiaries Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Service revenue Sales Revenue, Services, Net Management fee revenue Management Fees Revenue Revenue Revenues Costs and Expenses: Costs and Expenses [Abstract] Programming and production 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 and administrative Other Operating And Administrative Other operating and administrative expense recognized in the period not presented separately. Advertising, marketing and promotion Marketing and Advertising Expense Depreciation Depreciation Amortization Amortization of Intangible Assets Costs and expenses, total Costs and Expenses Operating income (loss) Operating Income (Loss) Other Income (Expense): Nonoperating Income (Expense) [Abstract] Interest expense Interest Expense Investment income (loss), net Investment Income, Nonoperating Equity in net income (losses) of investees, net Income (Loss) from Equity Method Investments Other income (expense), net Other Nonoperating Income (Expense) Nonoperating Income (Expense) Nonoperating Income (Expense) Income (loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax (expense) benefit Income Tax Expense (Benefit) Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock Net Income (Loss) Attributable To Noncontrolling Interests And Redeemable Subsidiary Preferred Stock Amount of net (income) loss attributable to noncontrolling interest and dividends on redeemable subsidiary preferred stock. Net income attributable to Parent Net Income (Loss) Attributable to Parent Comprehensive income attributable to Parent Comprehensive Income (Loss), Net of Tax, Attributable to Parent Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Cash Consideration Transferred By Comcast [Axis] Consideration Transferred By Comcast [Axis] Consideration Transferred By Comcast [Axis] Cash Consideration Transferred By Comcast [Domain] Cash Consideration Transferred By Comcast [Domain] [Domain] for Cash Consideration Transferred By Comcast [Axis] Cash Consideration Transferred By Comcast [Member] Consideration Transferred By Comcast [Member] Consideration Transferred By Comcast [Member] Tax Receivable Agreement [Axis] Tax Receivable Agreement [Axis] Tax Receivable Agreement Tax receivable agreement [Domain] Tax Receivable Agreement [Axis] [Domain] [Domain] for Tax Receivable Agreement Tax Receivable Agreement [Member] Tax Receivable Agreement [Member] Tax Receivable Agreement [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] DreamWorks Animation [Member] DreamWorks Animation [Member] Universal Studios Japan [Member] Universal Studios Japan [Member] Time Warner Cable Merger and Related Divestiture Transactions [Member] Time Warner Cable Merger and Related Divestiture Transactions [Member] NBCUniversal Media LLC [Member] NBCUniversal Media LLC [Member] NBCUniversal Media LLC [Member] Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed [Axis] Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed [Axis] Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed [Domain] Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed [Domain] Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed [Member] Member's contribution that represented Deferred Income Tax Assets and Other Tax-related Items recorded by Parent but excluded from net assets contributed [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Contribution from member MemberContribution Contribution of a business from member Cash consideration transferred Business Combination, Consideration Transferred Business acquisition share price (in dollars per share) Business Acquisition, Share Price Ownership percentage Ownership Percentage In New Company The parent entity's interest in net assets of the subsidiary, expressed as a percentage Ownership percentage by noncontrolling owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Transaction costs and transaction-related costs Transaction Costs and Transaction-Related Costs Transaction costs and transaction related costs recorded in the statement of income. Write-off of assets related to merger agreement termination Write-off of Assets Related to Merger Agreement Termination Amount of write-off of assets associated with the termination of a merger and/or divestiture transaction recorded in depreciation and amortization expenses. Earnings Per Share [Abstract] Basic EPS attributable to Comcast Corporation shareholders (in shares) Weighted Average Number of Shares Outstanding, Basic Assumed exercise or issuance of shares relating to stock plans (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted EPS attributable to Comcast Corporation shareholders (in shares) Weighted Average Number of Shares Outstanding, Diluted Basic earnings per common share attributable to Comcast Corporation shareholders (in dollars per share) Earnings Per Share, Basic Diluted earnings per common share attributable to Comcast Corporation shareholders (in dollars per share) Earnings Per Share, Diluted Income Tax Disclosure [Abstract] Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] Income Taxes [Line Items] Income Taxes [Line Items] [Line Items] for Income Taxes [Table] Income Taxes Income Tax Disclosure [Text Block] Film and television costs (see Note 6) Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Film and Television Costs Amount of film and television costs acquired at the acquisition date. Intangible assets (see Note 9) Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Working capital Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Working Capital The amount of working capital (current assets less current liabilities, including cash if any) acquired as of the acquisition date. Debt (see Note 10) Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt Tax receivable agreement Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Tax Receivable Agreement Amount of liability for a tax receivable agreement acquired at the acquisition date. Deferred income taxes (see Note 14) Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Other noncurrent assets and liabilities and other Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets and Liabilities The amount of acquisition cost of a business combination allocated to other noncurrent assets and liabilities of the acquired entity not otherwise disclosed separately. Identifiable net assets (liabilities) acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Noncontrolling interest Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value Goodwill Goodwill Cash consideration transferred by Comcast Investments, Debt and Equity Securities [Abstract] Equity And Cost Method Investments [Table] Equity And Cost Method Investments [Table] Equity And Cost Method Investments [Table] Fair Value, Equity And Cost Method Investments [Line Items] Fair Value, Equity And Cost Method Investments [Line Items] [Line Items] for Fair Value, Equity And Cost Method Investments [Table] Investment Summary Summary Investment Holdings [Table Text Block] Summarized Financial Information Equity Method Investments [Table Text Block] Investment Income (Loss), Net Components Of Investment Income Loss Net [Table Text Block] Tabular disclosure of investment income (loss), including, but not limited to gains on sales and exchanges of investments, other than temporary impairment losses and interest and dividend income. Other Industries [Abstract] Film And Television Cost [Table] Film And Television Cost [Table] Film And Television Cost [Table] Film And Television Cost [Line Items] Film And Television Cost [Line Items] [Line Items] for Film And Television Cost [Table] Film Costs: Theatrical Film Costs [Abstract] Released, less amortization Theatrical Film Costs, Released Completed, not released Theatrical Film Costs, Completed and Not Released In production and in development Theatrical Film Costs, In Production And In Development The amount of direct negative costs incurred in the production and development of a theatrical film, as well as allocations of production overhead and capitalized interest. Examples of direct negative costs include costs of story and scenario; compensation of cast, directors, producers, extras, and miscellaneous staff; costs of set construction and operations, wardrobe, and accessories; costs of sound synchronization; rental facilities on location; and postproduction costs such as music, special effects, and editing. Total film costs Theatrical Film Costs Television Costs: Direct-to-television Film Costs [Abstract] Released, less amortization Direct-to-television Film Costs, Released In production and in development Direct-to-Television Film Costs, In Production and In Development The amount of direct negative costs incurred in the production and development of a direct-to-television film, as well as allocations of production overhead and capitalized interest. Examples of direct negative costs include costs of story and scenario; compensation of cast, directors, producers, extras, and miscellaneous staff; costs of set construction and operations, wardrobe, and accessories; costs of sound synchronization; rental facilities on location; and postproduction costs such as music, special effects, and editing. Total television costs Direct-to-television Film Costs Programming rights, less amortization Programming Rights Less Amortization The carrying amount of total acquired programming rights, less amortization Total film costs, television costs and programming rights Total Film And Television Costs And Programming Rights After Amortization The carrying amount of owned films, television series and other television productions and the current and noncurrent portion of acquired television and cable networks programming rights recorded on the balance sheet. Owned films, television series and other television production costs include capitalizable production costs, production overhead, interest, development costs and acquired production costs. Film and television rights include multi-year programming arrangements, acquired movies, series and other programs. The carrying amount is stated at the lower of cost, less accumulated amortization, or net realizable/fair value at the balance sheet date. Less: Current portion of programming rights Programming Rights, Current The current portion of acquired television and cable networks programming rights recorded on the balance sheet. Includes multi-year programming arrangements, acquired movies, series and other programs. Carrying amount is stated at the lower of cost, less accumulated amortization, or net realizable value at the balance sheet date. Film and television costs Film And Television Costs The carrying amount of owned films, television series and other television productions and noncurrent acquired television and cable networks programming rights recorded on the balance sheet. Owned films, television series and other television production costs include capitalizable production costs, including direct costs, production overhead, print costs, development costs and interest. Film and television rights include multi-year programming arrangements, acquired movies, series and other programs. The carrying amount is stated at the lower of cost, less accumulated amortization, or net realizable/fair value at the balance sheet date. Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Financial Data by Business Segment Segment Reporting Disclosure [Text Block] Supplemental Financial Information [Abstract] Statement Of Cash Flows Supplemental Information Abstract Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Deferred gains (losses) on cash flow hedges Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Unrecognized gains (losses) on employee benefit obligations Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Cumulative translation adjustments Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Equity [Abstract] Schedule of common stock outstanding Schedule of Common Stock Outstanding Roll Forward [Table Text Block] Schedule of shares repurchased Class of Treasury Stock [Table Text Block] Schedule of accumulated other comprehensive income (loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Assets Assets [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Receivables, net Accounts Receivable, Net, Current Programming rights Deposits Deposits Assets, Current Other current assets Other Assets, Current Total current assets Assets, Current Investments Long-term Investments Investments in and amounts due from subsidiaries eliminated upon consolidation Investments in and amounts due from subsidiaries eliminated upon consolidation Investments in and amounts due from subsidiaries eliminated upon consolidation Property and equipment, net Property, Plant and Equipment, Net Franchise rights Indefinite-Lived Franchise Rights Other intangible assets, net Other Intangible Assets, Net Other noncurrent assets, net Other Assets, Noncurrent Total assets Assets Liabilities and Equity Liabilities and Equity [Abstract] Accounts payable and accrued expenses related to trade creditors Accounts Payable, Current Accrued participations and residuals Accrued Participations And Residuals, Current The total amount of participations, residual and royalty expenses due to another party in less than one year. Royalty expenses are due to content creators, including artists, authors and other talent; participations includes amounts to financial participants in films, including actors, directors, and producers, for contractually defined participations in a film's net profit or gross receipts; residuals include amounts due to unions and guilds. Accrued expenses and other current liabilities Accrued Expenses And Other Current Liabilities Including Deferred Revenue Accrued Expenses And Other Current Liabilities Including Deferred Revenue Current portion of long-term debt Debt, Current Total current liabilities Liabilities, Current Long-term debt, less current portion Long-term Debt and Capital Lease Obligations Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Other noncurrent liabilities Other Liabilities, Noncurrent Redeemable noncontrolling interests Redeemable Noncontrolling Interest, Equity, Carrying Amount Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock Common Stock, Value, Issued Other shareholders’ equity Other stockholders equity Other stockholders equity. Total Comcast Corporation shareholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Related Party Transactions Related Party Transactions Disclosure [Text Block] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Compensation and Retirement Disclosure [Abstract] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Deferred Compensation Plans [Member] Deferred Compensation Plans [Member] Deferred Compensation Plans [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Benefit obligation Deferred Compensation Plans Benefit Obligation Deferred compensation plans benefit obligation Interest expense Deferred Compensation Plans interest cost Deferred compensation plans interest cost Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Uncertain Tax Positions Indemnified By GE [Member] Uncertain Tax Positions Indemnified By Third Party [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Domestic Tax Authority [Member] Domestic Tax Authority [Member] Foreign Tax Authority [Member] Foreign Tax Authority [Member] Deferred Tax Impact of a Purchase of Noncontrolling Interest Deferred Tax Related to Purchase of Noncontrolling Interest Impact on deferred taxes related to the purchase of the remaining noncontrolling interest Foreign income before taxes Income (Loss) from Continuing Operations before Income Taxes, Foreign Deferred tax liability attributable to temporary differences in other comprehensive income Deferred Tax Liabilities, Other Comprehensive Income Decrease in deferred income tax liabilities related to acquisitions Business Acquisition Purchase Price Allocation Deferred Income Taxes Asset Liability Net1 Amount of acquisition cost of a business combination allocated to noncurrent deferred tax assets net of valuation allowance and noncurrent deferred tax liabilities. Net deferred tax liability, franchise rights Deferred Tax Liability Franchise Rights Amount of net deferred tax liabilities related to cable franchise rights that will remain unchanged unless an impairment is recognized or a cable franchise is disposed. Operating loss carryforwards Operating Loss Carryforwards Liability for uncertain tax positions Liability for Uncertainty in Income Taxes, Noncurrent Unrecognized tax benefits that would impact effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Change in income tax expense related to effectively settled uncertain tax positions Change In Income Tax Expense Related To Effectively Settled Uncertain Tax Positions Represents the change in income tax expense as a result of a reduction in the accrual for uncertain tax positions and related accrued interest on these tax positions, net of any indemnification. Unrecognized tax benefits, interest on income taxes accrued Unrecognized Tax Benefits, Interest on Income Taxes Accrued Supplemental Financial Information [Table] Supplemental Financial Information [Table] Supplemental Financial Information [Table] Supplemental Financial Information [Line Items] Supplemental Financial Information [Line Items] [Line Items] for Supplemental Financial Information [Table] Receivables, gross Accounts Receivable, Gross, Current Less: Allowance for returns and customer incentives Returns And Incentives Allowance, Current A valuation allowance for sales returns and other incentives. Less: Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Receivables, net Noncurrent receivables, net Accounts Receivable, Net, Noncurrent Accounting Changes and Error Corrections [Abstract] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Share Based Compensation New Accounting Pronouncement [Member] Share Based Compensation New Accounting Pronouncement [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] As Reported [Member] As Reported [Member] As Reported [Member] Effect of Adoption [Member] Effect of Adoption [Member] Effect of Adoption [Member] Upon Adoption [Member] Pro Forma [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Decrease in income tax expense New Accounting Pronouncement Or Change In Accounting Principle Effect Of Change On Income Tax Expense Amount Impact on income tax expense if new accounting pronouncement was adopted. Decrease in effective income tax rate New Accounting Pronouncement Or Change in Accounting Principle Effect Of Change On Income Tax Expense Rate Impact on effective tax rate if new accounting pronouncement was adopted. Increase in diluted earnings per share (in dollars per share) New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Diluted Earnings Per Share Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Significant Transactions Significant Transactions [Text Block] The disclosure of significant transactions entered into or completed during the period. Property and equipment (see Note 8) Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Noncontrolling interest Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Class A Common Stock [Member] Common Class A [Member] Class B Common Stock [Member] Common Class B [Member] Statement [Line Items] Statement [Line Items] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Treasury stock (in shares) Treasury Stock, Shares Commitments and Contingencies Disclosure [Abstract] Commitment And Contingencies [Table] Commitment And Contingencies [Table] Commitment And Contingencies [Table] Commitment And Contingencies [Line Items] Commitment And Contingencies [Line Items] [Line Items] for Commitment And Contingencies [Table] Schedule of minimum annual programming and talent commitments Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block] Schedule of rental expenses charged to operations Rental Expense [Table Text Block] Tabular disclosure of rental expense from operating leases for each period for which an income statement is presented. Pension Plan [Member] Pension Plan [Member] NBCUniversal Legacy Qualified Pension Plans [Member] NBCUniversal Qualified Pension Plan [Member] Retirement Investment Plans [Member] Retirement Investment Plans [Member] Retirement Investment Plans [Member] Postretirement and Other Benefits [Member] Postretirement and Other Benefits [Member] Stipend Plan [Member] Stipend Plan [Member] Stipend Plan [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Reduction of benefit obligations due to plan amendments Defined Benefit Plan, Plan Amendments Multiemployer Plans, Funded Status Multiemployer Plans, Funded Status Benefit obligation Defined Benefit Plan, Benefit Obligation Benefit obligations in excess of plan assets Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets Cash surrender value of life insurance policies Cash Surrender Value of Life Insurance Expenses related to retirement investment plans Defined Contribution Plan, Cost Recognized Funded percentage Multiemployer Plans, Funded Percentage Multiemployer Plans, Funded Percentage Mutliemployer plan contributions Multiemployer Plan, Period Contributions Severance Costs Other Restructuring Costs Valuation and Qualifying Accounts [Abstract] Valuation and Qualifying Accounts Disclosure [Table] Valuation and Qualifying Accounts Disclosure [Table] Valuation and Qualifying Accounts Disclosure [Line Items] Valuation and Qualifying Accounts Disclosure [Line Items] Schedule II - Valuation and Qualifying Accounts Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Line Items] Debt Instrument [Line Items] Schedule of Long-Term Debt Schedule of Debt [Table Text Block] Debt Maturities Schedule of Maturities of Long-term Debt [Table Text Block] Debt Borrowings Debt Borrowings [Table Text Block] Debt borrowings table. Debt Repayments and Repurchases Debt Repayments and Repurchases [Table Text Block] Debt Repayments and Repurchases [Text Block] Postretirement, Pension and Other Employee Benefit Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Operating Segments [Member] Operating Segments [Member] Corporate, Non-Segment [Member] Corporate, Non-Segment [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Cable Communications [Member] Cable Communications [Member] Cable Communications Member Cable Networks [Member] Cable Networks [Member] Cable Networks Member Broadcast Television [Member] Broadcast Television [Member] Broadcast Television Member Filmed Entertainment [Member] Filmed Entertainment [Member] Filmed Entertainment Member Theme Parks [Member] Theme Parks [Member] Theme Parks Member Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Balance, beginning of period Acquisitions Goodwill, Acquired During Period Adjustments Goodwill, Other Increase (Decrease) Foreign currency translation Goodwill, Foreign Currency Translation Gain (Loss) Balance, end of period Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Estimated Amortization Expense of Finite-Lived Intangible Assets Finite-Lived Intangible Assets [Line Items] 2017 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2018 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Five Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Schedule of Cost-method Investments [Table] Schedule of Cost-method Investments [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] BuzzFeed [Member] BuzzFeed [Member] Air Touch [Member] Air Touch [Member] Air Touch [Member] Vox Media [Member] Vox Media [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Schedule of Cost-method Investments [Line Items] Schedule of Cost-method Investments [Line Items] Fair value of cost method Investment redeemable preferred shares Fair Value Of Cost Method Investment Redeemable Preferred Shares The fair value of a cost method investment related to redeemable preferred shares. Number of preferred stock series Number of Preferred Stock Series Number of Preferred Stock Series Preferred stock aggregate redemption value Preferred Stock Aggregate Redemption Value Preferred stock aggregate redemption value Redeemable subsidiary preferred shares Carrying Amount Of Redeemable Preferred Stock Carrying amount of redeemable preferred stock Fair value of redeemable preferred shares Fair value of redeemable preferred shares Fair value of our redeemable subsidiary preferred shares and/or stock Nonredeemable subsidiary preferred shares Nonredeemable Preferred Stock Nonredeemable preferred stock issued by a wholly owned subsidiary of the company. Purchases of investments Cost Method Investments, Original Cost Postretirement and Pension Benefits Condensed Information On Our Postretirement And Pension Benefit Plans [Table Text Block] Tabular disclosure of the change in the benefit obligation of pension plans and/or other employee benefit plans from the beginning to the end of the period, showing separately, if applicable, the effects of the following: service cost, interest cost, contributions by plan participants, actuarial gains and losses, foreign currency exchange rate changes, benefits paid, plan amendments, business combinations, divestitures, curtailments, settlements, and special and contractual termination benefits. Disclosure also includes the certain accumulated beneift obligations dislcosure and the assumptions used to determine for pension plans and/or other employee benefit plans the benefit obligation and net benefit cost. Deferred Compensation Plans Deferred Compensation Plans [Text Block] Information regarding deferred compensation plans, including benefit obligations and related expense. Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property and Equipment Property, Plant and Equipment [Table Text Block] Current Assets: Assets, Current [Abstract] Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Current Liabilities: Liabilities, Current [Abstract] Program obligations Program Rights Obligations, Current Deferred revenue Deferred Revenue, Current Accrued expenses and other current liabilities Accrued Liabilities, Current Note payable to Comcast Notes Payable To Parent The total amount due to Parent, with respect to cash management arrangements under the matching revolving credit notes, as of the balance sheet date. Accrued participations, residuals and program obligations Accrued Participations Residuals And Program Obligations, Noncurrent The noncurrent amount of participations, residual, royalty expenses and program obligations due to another party. Royalty expenses are due to content creators, including artists, authors and other talent; participations includes amounts to financial participants in films, including actors, directors, and producers, for contractually defined participations in a film's net profit or gross receipts; residuals include amounts due to unions and guilds. Commitments and contingencies Commitments and Contingencies Preferred stock—authorized, 20,000,000 shares; issued, zero Preferred Stock, Value, Issued Member’s capital Members' Capital Common stock Additional paid-in capital Additional Paid in Capital Retained earnings Retained Earnings (Accumulated Deficit) Treasury stock, 436,395,514 Class A common shares Treasury Stock, Value Accumulated other comprehensive income (loss) Total NBCUniversal member’s equity Members' Equity Noncontrolling interests Members' Equity Attributable to Noncontrolling Interest Total equity Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest Document and Entity Information [Abstract] DocumentAndEntityInformationAbstract Document And Entity Information [Table] Document And Entity Information [Table] Document And Entity Information [Table] Document And Entity Information [Line Items] Document And Entity Information [Line Items] [Line Items] for Document And Entity Information [Table] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Public Float Entity Public Float Entity Current Reporting Status Entity Current Reporting Status Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Rent expense Operating Leases, Rent Expense Statement of Comprehensive Income [Abstract] Net income Unrealized gains (losses) on marketable securities, net of deferred taxes Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax Deferred gains (losses) on cash flow hedges, net of deferred taxes Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Amounts reclassified to net income: Amounts Reclassified To Net Income [Abstract] Realized (gains) losses on marketable securities, net of deferred taxes Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Realized (gains) losses on cash flow hedges, net of deferred taxes Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Employee benefit obligations, net of deferred taxes Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Currency translation adjustments, net of deferred taxes Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Net (income) loss attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Other comprehensive (income) loss attributable to noncontrolling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Long-term Debt, Fiscal Year Maturity [Abstract] Long-term Debt, Fiscal Year Maturity [Abstract] 2017 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2018 Long-term Debt, Maturities, Repayments of Principal in Year Two 2019 Long-term Debt, Maturities, Repayments of Principal in Year Three 2020 Long-term Debt, Maturities, Repayments of Principal in Year Four 2021 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Long-term Debt, Weighted-average Interest Rate, Fiscal Year Maturity [Abstract] Long-term Debt, Weighted-average Interest Rate, Fiscal Year Maturity [Abstract] Long-term Debt, Weighted-average Interest Rate, Fiscal Year Maturity [Abstract] 2017 Debt, Weighted Average Interest Rate On Debt Maturities During Next Twelve Months Debt, Weighted Average Interest Rate On Debt Maturities During Next Twelve Months 2018 Debt, Weighted Average Interest Rate On Debt Maturities In Year Two Debt, Weighted Average Interest Rate On Debt Maturities In Year Two 2019 Debt, Weighted Average Interest Rate On Debt Maturities In Year Three Debt, Weighted Average Interest Rate On Debt Maturities In Year Three 2020 Debt, Weighted Average Interest Rate On Debt Maturities In Year Four Debt, Weighted Average Interest Rate On Debt Maturities In Year Four 2021 Debt, Weighted Average Interest Rate On Debt Maturities In Year Five Debt, Weighted Average Interest Rate On Debt Maturities In Year Five Thereafter Debt, Weighted Average Interest Rate On Debt Maturities After Year Five Debt, Weighted Average Interest Rate On Debt Maturities After Year Five Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Guarantor Subsidiaries [Member] Guarantor Subsidiaries [Member] Maturing In Next Five Years [Member] Maturing In Next Five Years [Member] NBCUniversal Enterprise Senior Debt Securities [Member] Senior Notes [Member] Comcast Holdings' ZONES due October 2029 [Member] Comcast Holdings' ZONES due October 2029 [Member] Comcast Holdings' ZONES due October 2029 [Member] Comcast Holdings' ZONES due November 2029 [Member] Comcast Holdings' ZONES due November 2029 [Member] Comcast Holdings' ZONES due November 2029 Universal Studios Japan Term Loans [Member] Universal Studios Japan Term Loans [Member] Acquired Term Loans Principal amount of debt securities subject to guarantee Guarantee Obligations Current Principal Balance Principal amount of debt securities subject to guarantee. Principal amount of debt securities not subject to guarantee Non Guarantee Obligations Current Principal Balance Principal amount of debt instruments not guaranteed by Comcast Corporation, the cable guarantors nor NBCUniversal Media, LLC. Income Statement [Abstract] Amortization Total costs and expenses Operating income Investment income (loss), net Nonoperating income (expense) Income before income taxes Income tax expense Net income Net (income) loss attributable to noncontrolling interests Net income attributable to Parent Dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Declared Unaudited pro forma diluted earnings per common share attributable to Comcast Corporation shareholders, adjusted for the two for one stock split Diluted Earnings Per Share Pro Forma Quarterly Financial Information Disclosure [Abstract] Schedule of quarterly financial information Quarterly Financial Information [Table Text Block] NBCUniversal Enterprise [Member] NBCUniversal Enterprise [Member] NBCUniversal Enterprise Credit Facility [Member] NBCUniversal Enterprise Credit Facility [Member] Former Comcast And Comcast Cable Communications, LLC Revolving Credit Facility [Member] Comcast And Comcast Cable Communications, LLC Revolving Credit Facility [Member] Former NBCUniversal Enterprise Credit Facility [Member] Former NBCUniversal Enterprise Credit Facility [Member] Commercial Paper [Member] Commercial Paper [Member] NBCUniversal Enterprise Commercial Paper [Member] NBCUniversal Enterprise Commercial Paper [Member] Comcast And Comcast Cable Debt Securities [Member] Comcast And Comcast Cable Debt Securities [Member] Comcast Revolving Credit Facility [Member] Comcast Revolving Credit Facility [Member] Fair value of debt Long-term Debt, Fair Value Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Potential increase of maximum borrowing capacity Line of Credit facility, Potential increase to Maximum Borrowing Capacity Potential increased maximum borrowing capacity under the revolving credit facility, subject to approval of the lenders. Borrowing margin for LIBOR based borrowings Debt Instrument, Basis Spread on Variable Rate Amounts available under revolving credit facilities Line of Credit Facility, Remaining Borrowing Capacity Commercial paper capacity Commercial Paper Capacity Amount represents the maximum borrowing capacity under the commercial paper program. Unused irrevocable standby letters of credit Letters of Credit Outstanding, Amount Interest rate Debt Instrument, Interest Rate, Stated Percentage Ownership in cable holding company subsidiaries Ownership in cable holding company subsidiaries Represents the Company's ownership in its cable holding company subsidiaries. Related party aggregate principal amount senior notes not subject to guarantee Related Party Aggregate Principal Amount Senior Notes Not Subject To Guarantee Represents the related party aggregate principal amount of senior notes not subject to guarantee by NBCUniversal. Related party credit facility not subject to guarantee Related Party Credit Facility Not Subject To Guarantee Represents the related party credit facility not subject to guarantee by NBCUniversal. Related party liquidation preference preferred stock not subject to guarantee Related Party Liquidation Preference Preferred Stock Not Subject To Guarantee Represents the related party liquidation preference of preferred stock not subject to guarantee by NBCUniversal. Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Comcast And Consolidated Subsidiaries [Member] Comcast And Consolidated Subsidiaries [Member] Operating costs and expenses Operating Expenses Excluding Depreciation And Amortization Operating costs and expenses including amortization of film and television costs but excluding intangible amortization and depreciation. Other income (expense) Other Income Expense Related Party Represents all of the intercompany transactions with Comcast Corporation which are included in other income (expense) captions. Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Time Warner, Inc. [Member] Time Warner, Inc. [Member] Time Warner, Inc. [Member] Atairos [Member] Atairos [Member] Atairos [Member] Hulu [Member] Hulu [Member] Hulu member. The Weather Channel [Member] The Weather Channel [Member] The Weather Channel [Member] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Former CFO [Member] Former CFO [Member] Former CFO [Member] Maximum [Member] Maximum [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Term of agreement Term of agreement Term of agreement for Atairos Funding commitment Equity Method Investment, Funding Commitment Equity Method Investment, Funding Commitment Management fee funding commitment Equity Method Investment, Management Fee Funding Commitment Equity Method Investment, Management Fee Funding Commitment Funding commitment by management company investors Equity Method Investment, Funding Commitment by Management Company Investors Equity Method Investment, Funding Commitment by Management Company Investors Percent of losses Equity Method Investment, Percent of Losses Represents the percentage of any losses in an equity method investment that the Company is obligated to absorb. Percentage of residual returns Percentage of residual returns Represents the percentage of any residual returns that Comcast has the right to receive Purchases of investments Capital contribution to VIE The cash outflow associated with a capital contribution to a VIE accounted for as an equity method investment Capital Contribution to VIE accrued but not yet paid Capital Contribution Accrued But Not Yet Paid Capital contribution to a VIE recorded in the current period to be paid in a future period. Ownership percentage Equity Method Investment, Ownership Percentage Put/Call Period Equity Method Investment, Put or Call Period Equity Method Investment, Put or Call Period Deferred gain Equity Method Investment Deferred Gain This element represents disclosure of the amount of gain which has been deferred as the result of a dilution in our ownership percentage in an equity method investment which deferred gain has been reflected in the accompanying statement of financial position. Equity in net losses of investees Pretax gain on sale of investment Pretax Gain On Sale Of Investment Pretax gain recognized as a result of the sale of The Weather Channel's product and technology business to IBM Goodwill impairment loss from equity method investments Goodwill Impairment Loss From Equity Method Investments This item represents the entity's proportionate share for the period of a goodwill impairment charge recorded by its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. The amount is recorded in equity in net income (losses) of investees, net. Property and Equipment Property, Plant and Equipment Disclosure [Text Block] Tax Adjustments [Axis] Tax Adjustments [Axis] Tax Adjustments [Axis] Tax Adjustments [Domain] Tax Adjustments [Domain] Tax Adjustments [Domain] Differences Between Book and Tax Basis of Property and Equipment and Intangible Assets [Member] Property And Equipment And Intangible Assets [Member] Property And Equipment And Intangible Assets [Member] Differences Between Book and Tax Basis of Investments [Member] Investments [Member] Differences Between Book and Tax Basis of Indexed Debt Securities [Member] Indexed Debt Securities [Member] Indexed Debt Securities [Member] Differences Between Book and Tax Basis of Foreign Subsidiaries [Member] Foreign Subsidiaries And Undistributed Foreign Earnings [Member] Deferred Tax Assets: Deferred Tax Assets, Net [Abstract] Net operating loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards Deferred tax asset, other Deferred Tax Assets, Other Nondeductible accruals and other Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other Less: Valuation allowance Deferred Tax Assets, Valuation Allowance Total deferred tax assets, net of valuation allowance Deferred Tax Assets, Net of Valuation Allowance Deferred Tax Liabilities: Deferred Tax Liabilities, Net [Abstract] Deferred tax liabilities, other Deferred Tax Liabilities, Other Total deferred tax liabilities Deferred Tax Liabilities, Gross Net deferred tax liability Deferred Tax Liabilities, Net Statement of Cash Flows [Abstract] Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] 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] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Share-based compensation Share-based Compensation 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. Equity in net (income) losses of investees, net Cash received from investees Proceeds from Equity Method Investment, Dividends or Distributions Net (gain) loss on investment activity and other Gain (Loss) On Investments And Noncash Other Income (Expense) Net The net realized gain or loss on investments sold during the period and other income (expense), net, which, for cash flow reporting, is a component of proceeds from continuing operations. Deferred income taxes Deferred Income Tax Expense (Benefit) Changes in operating assets and liabilities, net of effects of acquisitions and divestitures: Increase (Decrease) in Operating Capital [Abstract] Current and noncurrent receivables, net Change In Current And Noncurrent Receivables Net The increase (decrease) during the reporting period in the amount of current and noncurrent receivables. Film and television costs, net Film And Television Costs Net Amount of net increase (decrease) in film and television costs. Accounts payable and accrued expenses related to trade creditors Increase (Decrease) in Accounts Payable and Accrued Liabilities Other operating assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by operating activities Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Cash paid for intangible assets Payments to Acquire Intangible Assets Acquisitions and construction of real estate properties Payments For Acquisitions And Construction Of Real Estate Properties The cash outflow for the acquisition and construction of buildings (properties) whether for investment or use. Acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired 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 during the period. Purchases of investments Payments to Acquire Investments Deposits Deposit Cash paid for deposits Other Payments for (Proceeds from) Other Investing Activities Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from (repayments of) short-term borrowings, net Proceeds from (Repayments of) Short-term Debt Proceeds from borrowings Proceeds from Issuance of Long-term Debt Repurchases and repayments of debt Repayments of Other Debt Proceeds from (repayments of) borrowings from Comcast, net Proceeds From Note Receivable Issued To And Borrowings From Comcast Represents the cash inflow from borrowings from Comcast for a note receivable issued to Comcast. Repurchases and retirements of common stock Payments for Repurchase of Common Stock Dividends paid Payments of Dividends Issuances of common stock Proceeds from Issuance of Common Stock Distributions to member Payments of Capital Distribution Distributions to noncontrolling interests Distributions To Noncontrolling Interest Holders The cash outflow related to distributions to noncontrolling interests. Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock Distributions To Noncontrolling Interests And Dividends For Redeemable Subsidiary Preferred Stock The cash outflow related to distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock. Other Proceeds from (Payments for) Other Financing Activities Net cash provided by (used in) financing activities Increase (decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of year Cash and cash equivalents, end of year Senior notes with maturities of 5 years or less, at face value [Member] Senior notes with maturities of 5 years or less, at face value [Member] Senior notes with maturities of 5 years or less [Member] Senior notes with maturities between 5 and 10 years, at face value [Member] Senior notes with maturities between 5 and 10 years, at face value [Member] Senior notes with maturities between 5 and 10 years [Member] Senior notes with maturities greater than 10 years, at face value [Member] Senior notes with maturities greater than 10 years, at face value [Member] Senior notes with maturities greater than 10 years [Member] Other Including Capital Lease Obligations [Member] Other Including Capital Lease Obligations [Member] Other Including Capital Lease Obligations [Member] Notes 5.50% Due 2029 [Member] Notes 5.50% Due 2029 [Member] Notes 5.50% due 2029 [Member] Weighted-Average Interest Rate Debt, Weighted Average Interest Rate Commercial paper Commercial Paper Revolving bank credit facilities Long-term Line of Credit Term loans Other Long-term Debt Senior notes Senior Notes Other, including capital lease obligations Other Borrowings Debt issuance costs, premiums, discounts and fair value adjustments for hedged positions, net Debt issuance costs, premiums, discounts and fair value adjustments for hedged positions The carrying amount as of the balance sheet date for the net impact of debt issuance costs, premiums, discounts and fair value adjustments for hedged positions. Total debt Debt and Capital Lease Obligations Less: Current portion Long-term debt Capital expenditures incurred but not yet paid Capital Expenditures Incurred but Not yet Paid Dividends payable Dividends Payable Dividends payable (in dollars per share) Dividends Payable, Amount Per Share Fair value equity securities settlement Fair Value Equity Securities Settlement Fair value method equity securities used to settle our obligations under prepaid forward sale agreements in the period. Carrying Value Of Related Party Contractual Obligation [Member] Carrying Value Of Related Party Contractual Obligation [Member] NBCUniversal Holdings Preferred Stock [Member] NBCUniversal Holdings Preferred Stock [Member] Former Comcast And NBCUniversal Revolving Credit Agreements [Member] FormerComcastAndNBCUniversalRevolvingCreditAgreements [Member] Former Comcast And NBCUniversal Revolving Credit Agreements [Member] Comcast and NBCUniversal Revolving Credit Agreements [Member] Comcast and NBCUniversal Revolving Credit Agreements [Member] Comcast and NBCUniversal Revolving Credit Agreements [Member] Revolving credit agreement capacity Revolving Credit Agreement Capacity The maximum amount of borrowing or lending capacity with respect to the cash management arrangement between Comcast and NBCUniversal under the revolving credit agreement. Preferred stock, dividend rate Preferred Stock, Dividend Rate, Percentage Preferred stock liquidation preference value Preferred Stock, Liquidation Preference, Value Senior 2.875% Notes Due 2016 [Member] Senior 2.875% Notes Due 2016 [Member] Senior 4.95% Notes Due 2016 [Member] Senior 4.95% Notes Due 2016 [Member] NBCUniversal Enterprise Senior Notes Due 2016 [Member] NBCUniversal Enterprise Senior Notes Due 2016 [Member] DreamWorks Assumed Debt [Member] DreamWorks Assumed Debt [Member] DreamWorks Assumed Debt [Member] Other Long-Term Debt [Member] Other Long-Term Debt [Member] Other Long-Term Debt [Member] Repurchases and repayments of debt Repayments of Assumed Debt Repayments of Assumed Debt Related Party Transactions Condensed Financial Statements Schedule of Related Party Transactions [Table Text Block] Recent Accounting Pronouncements [Table] Recent Accounting Pronouncements [Table] Recent Accounting Pronouncements [Table] Recent Accounting Pronouncements [Line Items] Recent Accounting Pronouncements [Line Items] [Line Items] for Recent Accounting Pronouncements [Table] Recent Accounting Pronouncements New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Business And Basis Of Presentation [Table] Business And Basis Of Presentation [Table] Business And Basis Of Presentation [Table] Business And Basis Of Presentation [Line Items] Business And Basis Of Presentation [Line Items] Business And Basis Of Presentation Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] Condensed Consolidating Financial Statements Condensed Financial Statements [Table Text Block] Gains on sales and exchanges of investments, net Realized Investment Gains (Losses) Investment impairment losses Other than Temporary Impairment Losses, Investments Unrealized gains (losses) on securities underlying prepaid forward sale agreements Unrealized Gain (Loss) on Securities Mark to market adjustments on derivative component of prepaid forward sale agreements and indexed debt instruments Mark To Market Adjustment on Derivative Component Of Prepaid Forward Sale Agreements Mark To Market Adjustment on Derivative Component Of Prepaid Forward Sale Agreements and indexed debt instruments. Interest and dividend income Investment Income, Interest and Dividend Other, net Other Investment Income Loss Net Nonoperating income (losses), net from investment holdings recorded in the income statement that are not separately stated. Investment income (loss), net Financial Data by Business Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Cable Communications Segment Revenue Sources Revenue from External Customers by Products and Services [Table Text Block] Revenue From External Customers By Geographic Areas Revenue from External Customers by Geographic Areas [Table Text Block] NBC Universal Media LLC [Member] Revenue Business Acquisition, Pro Forma Revenue Net income Business Acquisition, Pro Forma Net Income (Loss) Net income attributable to parent company Business Acquisition, Pro Forma Net Income (Loss) Attributable to Parent The pro forma portion of profit or loss, net of income taxes, which is attributable to the parent as if the business combination had been completed at the beginning of the period. Basic earnings per common share attributable to Comcast Corporation shareholders (in dollars per share) Business Acquisition, Pro Forma Earnings Per Share, Basic Diluted earnings per common share attributable to Comcast Corporation shareholders (in dollars per share) Business Acquisition, Pro Forma Earnings Per Share, Diluted Revenue of Acquiree Since Acquisition Date Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Net income of Acquiree Since Acquisition Date Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Schedule of Business Acquisitions, by Acquisition Schedule of Business Acquisitions, by Acquisition [Table Text Block] Unaudited Pro Forma Information Business Acquisition, Pro Forma Information [Table Text Block] Programming and Talent Commitments Contractual Obligation, Fiscal Year Maturity [Abstract] 2017 Contractual Obligation, Due in Next Fiscal Year 2018 Contractual Obligation, Due in Second Year 2019 Contractual Obligation, Due in Third Year 2020 Contractual Obligation, Due in Fourth Year 2021 Contractual Obligation, Due in Fifth Year Thereafter Contractual Obligation, Due after Fifth Year Operating Leases Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2017 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2018 Operating Leases, Future Minimum Payments, Due in Two Years 2019 Operating Leases, Future Minimum Payments, Due in Three Years 2020 Operating Leases, Future Minimum Payments, Due in Four Years 2021 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Equity Stockholders' Equity Note Disclosure [Text Block] Current Expense (Benefit): Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) Current income tax expense (benefit) Current Income Tax Expense (Benefit) Deferred Expense (Benefit): Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Foreign Deferred Foreign Income Tax Expense (Benefit) Deferred income tax expense (benefit) Withholding tax expense Foreign Withholding Tax Expense The amount of tax liability incurred by the Company in licensing its content to non-US territories. U.S. domestic tax expense Domestic Tax Expense Benefit Amount of current and deferred income tax expense (benefit) attributable to income (loss) from continuing domestic operations within the country of domicile of the entity. Income tax expense Unrealized gains (losses) on marketable securities Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Schedule of recognized share-based compensation expense Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block] Schedule of stock option and restricted share units activity Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block] Schedule of stock option and restricted share units fair value and significant assumptions Stock Option Fair Value and Significant Assumptions [Text Block] Stock option fair value and significant assumptions Redeemable Subsidiary Preferred Stock [Member] Redeemable Preferred Stock [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Workforce Subject to Collective Bargaining Arrangements [Member] Workforce Subject to Collective Bargaining Arrangements [Member] Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] Number of employees covered under collective bargaining agreements Number Of Employees Covered Under Collective Bargaining Agreements Number of employees covered by collective bargaining agreements. Percentage Of Employees Covered Under Collective Bargaining Agreements Expired Or Scheduled To Expire During The Next Year Concentration Risk, Percentage Carrying value of contractual obligation Carrying value of contractual obligation Carrying value of future obligation classified as a liability which is no longer recorded at fair value. Contractual value of a potential obligation if option had been exercisable Contractual Value of a Potential Future Obligation if Option Had Been Exercisable Contractual value of a potential future obligation if option had been exercisable based on a contractual formula on a specified date. Payment for contingent consideration Payment For Contingent Consideration Liability, Financing Activities Amount paid for the settlement of a contingent consideration obligation. Gain on settlement of contingent consideration Gain Related to Contingent Consideration Settlement Gain related to the settlement of a contingent consideration obligation recorded in other income (expense), net. Redeemable subsidiary preferred stock, dividend rate Redeemable subsidiary preferred stock, put period Preferred Stock, Put Period The holders have the right to cause NBCUniversal Enterprise to redeem their shares at a price equal to the liquidation preference plus accrued but unpaid dividends for a 30 day period beginning on March 19, 2020 and thereafter on every third anniversary of such date (each such date, a “put date”). Redeemable subsidiary preferred stock, call period Preferred Stock, Call Period Shares of preferred stock can be called for redemption by NBCUniversal Enterprise at a price equal to the liquidation preference plus accrued but unpaid dividends one year following the put date applicable to such shares. Temporary equity, fair value of redeemable subsidiary preferred stock Temporary Equity, Fair Value Of Redeemable Subsidiary Preferred Stock Temporary Equity, Fair Value of our redeemable subsidiary preferred stock. Accounting Policies [Abstract] Accounting Policies [Table] Accounting Policies [Table] Accounting Policies [Table] Accounting Policies [Line Items] Accounting Policies [Line Items] [Line Items] for Accounting Policies [Table] Impairment Testing of Investments Investments Impairment [Policy Text Block] Disclosure of accounting policy for recognizing and measuring the impairment of long-lived assets. Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Cost Method Investments Cost Method Investments, Policy [Policy Text Block] Basis of Presentation Consolidation, Policy [Policy Text Block] Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] New Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Cable Communications Programming Expenses Cable Communications Programming Expenses Policy [Text Block] Cable Communications Programming Expenses Advertising Expenses Advertising Cost, Policy, Expensed Advertising Cost [Policy Text Block] Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Derivative Financial Instruments Derivatives, Policy [Policy Text Block] Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Asset Retirement Obligations Asset Retirement Obligations and Environmental Cost, Policy [Policy Text Block] Film And Television Costs Film And Television Costs [Policy Text Block] Describes an entity's accounting policy for film and television costs. This accounting policy also may address how an entity assesses and measures impairment of film and television costs. Investments Investment, Policy [Policy Text Block] Property and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Indefinite-Lived Intangible Assets Goodwill and Intangible Assets, Intangible Assets, Indefinite-Lived, Policy [Policy Text Block] Definite-Lived Intangible Assets Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Share-Based Compensation Compensation Related Costs, Policy [Policy Text Block] Postretirement and Pension Benefits Pension and Other Postretirement Plans, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Accounting Policies Significant Accounting Policies [Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Class A Special Common Stock [Member] Class A Special Common Stock [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Redeemable Noncontrolling Interests And Redeemable Subsidiary Preferred Stock [Member] Redeemable Noncontrolling Interests And Redeemable Subsidiary Preferred Stock [Member] Redeemable Noncontrolling Interests and Redeemable Subsidiary Preferred Stock [Member] Redeemable Noncontrolling Interest [Member] Redeemable Noncontrolling Interest [Member] Member's Capital [Member] Member's Capital [Member] Common Stock [Member] Common Stock [Member] Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Treasury Stock at Cost [Member] Treasury Stock [Member] Accumulated Other Comprehensive Income (Loss) [Member] AOCI Attributable to Parent [Member] Noncontrolling Interest [Member] Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance Beginning Balance Stock compensation plans Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Repurchases and retirements of common stock Stock Repurchased and Retired During Period, Value Employee stock purchase plans Stock Issued During Period, Value, Employee Stock Purchase Plan Dividends declared Dividends, Common Stock, Cash Issuance of subsidiary shares to noncontrolling interests NoncontrollingInterestIncreaseFromEquityIssuanceOrSaleOfParentEquityInterest Noncontrolling interest increase from equity issuance or sale of parent equity interest Contributions From And Distributions To Noncontrolling Interests ContributionsFromAndDistributionsToNoncontrollingInterests Contributions from and distributions to n oncontrolling interests Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Reclassification of Class A Special common stock Reclassification Of Common Stock Represents the change in dollar amount due to the Common Stock Reclassification Universal Studios Japan Universal Studios Japan Equity impact related to the acquisition of Universal Studios Japan Other Stockholders' Equity, Other Net income (loss) Equity Profit Loss Profit or loss as represented on the statement of changes in equity. Ending Balance Ending Balance Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Beginning Balance Issuance of subsidiary shares to noncontrolling interests, temporary equity Noncontrolling Interest, Increase from Subsidiary Equity Issuance 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. Other Temporary Equity, Other Changes Net income (loss) Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Ending Balance Supplemental Financial Information Additional Financial Information Disclosure [Text Block] Other Equity Method Investments [Member] Other Equity Method Investments [Member] Other Equity Method Investments [Member] Other Cost Method Investments [Member] Other Cost Method Investments [Member] Other Cost Method Investments [Member] Fair Value Method Marketable Securities Equity method Equity Method Investments Cost method Cost Method Investments Total Investments Investments Less: Current investments Short-term Investments Noncurrent investments Note payable to Comcast Note Payable To Parent The total amount due to Parent, with respect to cash management arrangements under the matching revolving credit notes, as of the balance sheet date. Schedule for the components of income tax expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of items that effect income tax expense Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of the components of net deferred tax liability Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Reconciliation of unrecognized tax benefits Summary of Income Tax Contingencies [Table Text Block] Schedule of changes related to adoption of new accounting pronouncement Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Film and Television Costs Schedule Of Film And Television Costs [Table Text Block] Schedule Of Film And Television Costs [Table Text Block] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted Stock Units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] Stock options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Weighted-average exercise price of awards granted during the year (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Stock options outstanding (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Weighted-average exercise price of shares outstanding (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Awards granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Awards nonvested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Weighted-average fair value at grant date of nonvested awards (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Postretirement Benefit Plan [Member] Other Postretirement Benefit Plan [Member] Plan funded status and recorded benefit obligation Defined Benefit Plan, Funded Status of Plan Portion of benefit obligation not yet recognized in benefits expense Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax Benefits expense Pension and Other Postretirement Benefit Expense Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Adjustments To Capitalized Film And Stage Play Production Costs [Axis] Adjustments To Capitalized Film And Stage Play Production Costs [Axis] Adjustments To Capitalized Film And Stage Play Production Costs [Axis] Adjustments To Capitalized Film And Stage Play Production Costs [Domain] Adjustments To Capitalized Film And Stage Play Production Costs [Domain] [Domain] for Adjustments To Capitalized Film And Stage Play Production Costs [Axis] Adjustments To Capitalized Film And Stage Play Production Costs [Member] Adjustments To Capitalized Film And Stage Play Production Costs [Member] Adjustments To Capitalized Film And Stage Play Production Costs [Member] Amortization of completed film and television production expected to be amortized during the next fiscal year Film Costs, Amortized in Next Operating Cycle Expected amortization percentage of released and unamortized film and television costs during the next three fiscal years Percentage of Unamortized Film Costs Remaining unamortized costs of acquired film and television libraries Film And Television Library Costs Unamortized The remaining amount of costs related to film and television libraries that are expected to be amortized. Amortization period of acquired film and television library costs Acquired Film and Television Library Costs, Amortization Period Acquired Film and Television Library Costs, Amortization Period Expected amortization percentage of unamortized acquired film and television library costs during the next three fiscal years Percentage Of Acquired Film And Television Libraries To Be Amortized In The Next Three Years The percentage of unamortized acquired film and television library costs that are expected to be amortized within three years from the date of the balance sheet. Adjustments to capitalized film and stage play production costs Asset Impairment Charges Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Video Customers [Member] Video Customers [Member] Video Customers [Member] High-speed Internet Customers [Member] High-speed Internet Customers [Member] High-speed Internet Customers [Member] Voice Customers [Member] Voice Customers [Member] Voice Customers [Member] NBCUniversal [Member] NBCUniversal [Member] Stockholders' Equity Note, Stock Split, Conversion Ratio Stockholders' Equity Note, Stock Split, Conversion Ratio Number of reportable segments Number of Reportable Segments Total customer relationships Total Customer Relationships Represents the number of residential and business customers that subscribe to at least one of our three primary services of video, high-speed Internet and voice. Number of customers Number Of Customers Represents the number of customers that subscribe to our services. Long-Term Debt Debt Disclosure [Text Block] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves [Domain] Valuation Allowances and Reserves [Domain] Allowance for doubtful accounts [Member] Allowance for Doubtful Accounts [Member] Allowance for returns and customer incentives [Member] Allowance for Sales Returns [Member] Valuation allowance on deferred tax assets [Member] Valuation Allowance of Deferred Tax Assets [Member] Movement in Valuation Allowances and Reserves [Roll Forward] Movement in Valuation Allowances and Reserves [Roll Forward] Balance at Beginning of Year Valuation Allowances and Reserves, Balance Additions Charged to Costs and Expenses Valuation Allowances and Reserves, Additions for Charges to Cost and Expense Deductions from Reserves Valuation Allowances and Reserves, Deductions Balance at End of Year Schedule of receivables, net Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Schedule of cash payments for interest and income taxes Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Cash Payments for Interest and Income Taxes Supplemental Cash Flow Information [Abstract] Interest Interest Paid, Net Income taxes Income Taxes Paid, Net Equity [Table] Equity [Table] Equity [Table] Equity [Line Items] Equity [Line Items] [Line Items] for Equity [Table] Common stock, shares outstanding at beginning of period (in shares) Stock compensation plans (in shares) Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Repurchases and retirements of common stock (in shares) Stock Repurchased and Retired During Period, Shares Employee stock purchase plan (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Reclassification of Class A Special common stock (in shares) Reclassification of Class A Special common stock (in shares) Represents the change in share amount due to the Class A Special Common Stock Reclassification Other (in shares) Stock Issued During Period, Shares, Other Common stock, shares outstanding at end of period (in shares) Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Software [Member] Computer Software, Intangible Asset [Member] Number of divisions Number of Divisions Number of Divisions Finite-lived intangible asset amortization period Finite-Lived Intangible Asset, Useful Life Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] New Authorization [Member] New Authorization [Member] Voting power Common Stock Voting Power Common Stock Voting Power Number of votes entitled of each class B common stock Number Of Votes Entitled Of Each Class B Common Stock Number of votes entitled to vote for each share of Class B common stock share. Shares awarded per exchanged share (in shares) Number Of Class A Common Shares Entitled in Exchange For Each Class A Special Common Stock Number of Class A Common Stock Entitled in Exchange for Each Class A Special Common Stock Stock repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Current assets Equity Method Investment, Summarized Financial Information, Current Assets Noncurrent assets Equity Method Investment, Summarized Financial Information, Noncurrent Assets Current liabilities Equity Method Investment, Summarized Financial Information, Current Liabilities Noncurrent liabilities Equity Method Investment, Summarized Financial Information, Noncurrent Liabilities Revenue Equity Method Investment, Summarized Financial Information, Revenue Operating income (loss) Operating Income [Summarized Financial Information] The amount of operating income reported by an equity method investment of the entity. Net income (loss) Equity Method Investment, Summarized Financial Information, Net Income (Loss) Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Cable Distribution System [Member] Cable Distribution System [Member] Cable Distribution System [Member] Customer Premise Equipment [Member] Customer Premise Equipment [Member] Customer premise equipment [Member] Other Equipment [Member] Other Capitalized Property Plant and Equipment [Member] Building and Leasehold Improvements [Member] Building and Building Improvements [Member] Furniture, Fixtures and Equipment [Member] Furniture and Fixtures [Member] Construction in Process [Member] Construction in Progress [Member] Land [Member] Land [Member] Weighted-Average Original Useful Life Property, Plant and Equipment, Useful Life Property and equipment, at cost Property, Plant and Equipment, Gross Less: Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property and equipment, net Film and Television Costs Film And Television Costs Disclosure [Text Block] Film and Television costs Disclosure [Text Block] Employee Stock Option [Member] Employee Stock Option [Member] Employee Stock Purchase Plans [Member] Employee Stock [Member] Recognized share-based compensation expense Allocated Share-based Compensation Expense Schedule of Indefinite and Finite-Lived Intangible Assets [Table] Schedule of Indefinite and Finite-Lived Intangible Assets [Table] Schedule of assets, excluding financial assets and goodwill, lacking physical substance. Schedule of Indefinite and Finite-Lived Intangible Assets [Line Items] Schedule of Indefinite and Finite-Lived Intangible Assets [Line Items] [Line Items] for Schedule of assets, excluding financial assets and goodwill, lacking physical substance. Total Intangible Assets, Gross (Excluding Goodwill) Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Franchise Rights [Member] Franchise Rights [Member] Trade Names [Member] Trade Names [Member] FCC Licenses [Member] Licensing Agreements [Member] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Gross Carrying Amount Indefinite-Lived Intangible Assets (Excluding Goodwill) Intangible Assets By Major Class [Axis] Intangible Assets By Major Class [Axis] Intangible Assets Major Class Name [Domain] Intangible Assets Major Class Name [Domain] Customer Relationships [Member] Customer Relationships [Member] Cable franchise renewal costs and contractual operating rights [Member] Cable franchise renewal costs and contractual operating rights [Member] Patents and other technology rights [Member] Patents and other technology rights [Member] Other agreements and rights [Member] Other Intangible Assets [Member] Weighted-Average Original Useful Life Gross Carrying Amount Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Goodwill And Intangible Assets [Table] Goodwill And Intangible Assets [Table] Goodwill And Intangible Assets [Table] Goodwill And Intangible Assets [Line Items] Goodwill And Intangible Assets [Line Items] [Line Items] for Goodwill And Intangible Assets [Table] Schedule of Goodwill Schedule of Goodwill [Table Text Block] Other Intangible Assets Intangible Assets Disclosure [Text Block] Amortization of Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Quarterly Financial Information [Table] Quarterly Financial Information [Table] Quarterly Financial Information [Table] Verizon Wireless [Member] Verizon Wireless [Member] Verizon Wireless [Member] Quarterly Financial Information [Line Items] Quarterly Financial Information [Line Items] [Line Items] for Quarterly Financial Information [Table] Operating income Net Income (Loss) Attributable to Parent Income resulting from an agency agreement Income Resulting From An Agency Agreement Income recognized in connection with the settlement of amounts owed to us under an agency agreement Income Resulting From An Agency Agreement, Net of Tax Income Resulting From An Agency Agreement, Net of Tax Income, net of tax, recognized in connection with the settlement of amounts owed to us under an agency agreement Weighted average fair value of RSUs (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 Stock option fair value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Stock Option Valuation Assumptions: Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected option life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Balance, January 1 Unrecognized Tax Benefits Additions based on tax positions related to the current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Additions based on tax positions related to prior years Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Additions from acquired subsidiaries Unrecognized Tax Benefits Increases Resulting From Acquired Subsidiaries Unrecognized Tax Benefits Increases Resulting From Acquired Subsidiaries Reductions for tax positions of prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Reductions due to expiration of statutes of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Settlements with tax authorities Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Balance, December 31 Condensed Consolidating Financial Information Condensed Financial Information of Parent Company Only Disclosure [Text Block] Class of Treasury Stock [Table] Class of Treasury Stock [Table] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Cash consideration Shares repurchased (in shares) Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Net transactions with affiliates Net transactions with affiliates Net transactions with affiliates. Residential Video Products And Services [Member] Residential Video Products And Services [Member] Residential Video Products And Services [Member] Residential High-speed Internet Products And Services [Member] Residential High-speed Internet Products And Services [Member] Residential High-speed Internet Products And Services [Member] Residential Voice Products And Services [Member] Residential Voice Products And Services [Member] Residential Voice Products And Services [Member] Business Products And Services [Member] Business Products And Services [Member] Business Products And Services [Member] Advertising Products And Services [Member] Advertising Products And Services [Member] Advertising Products And Services [Member] Other Products And Services [Member] Other Products And Services [Member] Other Products And Services [Member] Franchise And Other Regulatory Fees [Member] Franchise And Other Regulatory Fees [Member] Franchise And Other Regulatory Fees [Member] Consolidation, Eliminations [Member] Consolidation, Eliminations [Member] Non United States [Member] Non-US [Member] United States [Member] UNITED STATES Operating income (loss) before depreciation and amortization Operating Income Excluding Depreciation And Amortization This element represents the operating income or loss excluding depreciation and amortization. Capital Expenditures Cash Paid for Intangible Assets Cable segment revenue types as percentage of total cable revenue Cable segment revenue types as percentage of total cable revenue Cable segment revenue types as percentage of total cable revenue Segment Reporting, Disclosure of Major Customers Segment Reporting, Disclosure of Major Customers Unrealized gains (losses) on marketable securities, deferred taxes Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Deferred gains (losses) on cash flow hedges, deferred taxes Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Realized (gains) losses on marketable securities, deferred taxes Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Realized (gains) losses on cash flow hedges, deferred taxes Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax Employee benefit obligations, deferred taxes Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Currency translation adjustments, deferred taxes Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Quarterly Financial Information (Unaudited) Quarterly Financial Information [Text Block] Computation of diluted EPS Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Earnings Per Share Earnings Per Share [Text Block] Uncertain And Effectively Settled Tax Positions, Net [Member] Uncertain And Effectively Settled Tax Positions, Net [Member] Uncertain And Effectively Settled Tax Positions, Net Member Accrued Interest On Uncertain And Effectively Settled Tax Positions Net [Member] Accrued Interest On Uncertain And Effectively Settled Tax Positions Net [Member] Accrued Interest On Uncertain And Effectively Settled Tax Positions Net [Member] Federal tax at statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount State income taxes, net of federal benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Foreign income taxes, net of federal credit Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Nontaxable income attributable to noncontrolling interests Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Amount Other adjustments Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Unrecognized pretax compensation expense on nonvested awards Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Share-based compensation arrangement by share-based payment award, award vesting period in years Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Period from grant date that an equity-based award expires Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Senior 3.15% Notes Due 2026 [Member] Senior 3.15% Notes Due 2026 [Member] Senior 4.05% Notes Due 2046 [Member] Senior 4.05% Notes Due 2046 [Member] Senior 2.35% Notes Due 2027 [Member] Senior 2.35% Notes Due 2027 [Member] Senior 3.40% Notes Due 2046 [Member] Senior 3.40% Notes Due 2046 [Member] Senior 2.75% Notes Due 2023 [Member] Senior 2.75% Notes Due 2023 [Member] Senior 3.20% Notes Due 2036 [Member] Senior 3.20% Notes Due 2036 [Member] Senior 1.625% Notes Due 2022 [Member] Senior 1.625% Notes Due 2022 [Member] Other Borrowings [Member] Other Borrowings [Member] Other Borrowings [Member] Debt face amount Debt Instrument, Face Amount Other Borrowings Debt Instrument Unamortized Discount Premium Net and Other Borrowings Amount of debt discount (premium) and other borrowings.