DocumentAndEntityInformationAbstract Document and Entity Information Statement [Table] Class of Stock [Axis] Class of Stock [Domain] Class B Common Stock [Member] Common Stock B Statement [Line Items] Document Type Amendment Flag Document Period End Date Document Fiscal Year Focus Document Fiscal Period Focus Trading Symbol Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Condensed Consolidated Balance Sheet Class A Common Stock [Member] Common Stock A Assets Cash and cash equivalents Cash and cash equivalents, end of period Cash and cash equivalents, beginning of period Cash and Cash Equivalents, at Carrying Value, Total Short Term Investments Less: Current investments Less: Current investments Short-term Investments, Total Investments Accounts receivable, less allowance for doubtful accounts of $196 and $175 Accounts receivable, net Receivables, net Receivables, net Monetized receivables outstanding 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. Programming Rights Current Programming rights Less: Current portion of programming rights Other current assets Total current assets Current Assets Total current assets 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 fair value at the balance sheet date. Film And Television Cost Film and television costs Film and television costs Film and television costs Long Term Investments Noncurrent investments Noncurrent investments Investments Property and equipment, net of accumulated depreciation of $31,229 and $27,810 Property, Plant and Equipment, Net, Ending Balance Property, Plant and Equipment, Net, Beginning Balance Property and equipment, net Property and equipment, net Property and equipment, net Franchise rights Cable franchise rights Goodwill Goodwill ending balance Goodwill beginning balance Goodwill Other intangible assets, net of accumulated amortization of $9,518 and $8,711 Other intangible assets, net Finite-Lived Intangible Assets, Net, Total Other intangible assets, net Other noncurrent assets, net Other Assets, Noncurrent, Total us-gaap_Assets Total assets Total assets Assets Liabilities and Equity Accounts payable and accrued expenses related to trade creditors Accounts Payable, Current, Total Accrued Participations and Residuals Current Accrued Participations and Residuals Current Accrued participations and residuals Accrued expenses and other current liabilities Accrued Liabilities, Current, Total Current portion of long-term debt Less: current portion Debt, Current, Total Total current liabilities Total current liabilities Long-term debt, less current portion Long-term debt, less current portion Long-term Debt and Capital Lease Obligations, Total Carrying Value Deferred Tax Liabilities Noncurrent Deferred income taxes Other noncurrent liabilities Other Liabilities, Noncurrent, Total Commitments And Contingencies 2009 Commitments and contingencies (Note 0) Commitments and contingencies (Note 16) Redeemable noncontrolling interests Equity: Preferred stock-authorized, 20,000,000 shares; issued, zero Preferred Stock, Value, Issued, Ending Balance Preferred Stock, Value, Issued, Beginning Balance Preferred Stock, Value, Issued, Total Class B common stock, $0.01 par value-authorized, 75,000,000 shares; issued and outstanding, 9,444,375 Common Stock, Value, Issued, Ending Balance Common Stock, Value, Issued, Beginning Balance Common stock Common Stock, Value, Issued, Total Additional Paid In Capital Additional Paid in Capital, Ending Balance Additional Paid in Capital, Beginning Balance Additional Paid in Capital, Total Additional paid-in capital Retained Earnings Accumulated Deficit Retained Earnings (Accumulated Deficit), Ending Balance Retained Earnings (Accumulated Deficit), Beginning Balance Retained Earnings (Accumulated Deficit), Total Retained earnings Treasury stock, 365,460,750 Class A common shares and 70,934,764 Class A Special common shares Treasury stock, 365,460,750 Class A common shares and 70,934,764 Class A Special common shares Treasury Stock, Value, Ending Balance Treasury Stock, Value, Beginning Balance Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance Accumulated other comprehensive income (loss), net of deferred taxes Accumulated other comprehensive income (loss), net of deferred taxes Accumulated other comprehensive income (loss) Total Comcast Corporation shareholders' equity Stockholders' Equity Attributable to Parent, Ending Balance Stockholders' Equity Attributable to Parent, Beginning Balance Total Comcast Corporation shareholders' equity Minority Interest Stockholders' Equity Attributable to Noncontrolling Interest, Ending Balance Stockholders' Equity Attributable to Noncontrolling Interest, Beginning Balance Stockholders' Equity Attributable to Noncontrolling Interest, Total Noncontrolling interests Total equity Balance Balance Total equity Total liabilities and equity Total Liabilities Total liabilities and equity Preferred stock, authorized Preferred stock, issued Preferred Stock, Shares Issued, Total Common stock, par value Common stock, authorized Common stock, issued Common Stock, Shares, Issued, Total Common stock, outstanding Common Stock, Shares, Outstanding, Ending Balance Common Stock, Shares, Outstanding, Beginning Balance Balance Balance Treasury stock, common shares Treasury Stock, Shares, Ending Balance Treasury Stock, Shares, Beginning Balance Condensed Consolidated Statement of Income Revenue Revenues, Total Revenue Costs and Expenses: Operating Costs and Expenses Excluding Depreciation And Amortization Operating Costs and Expenses Excluding Depreciation And Amortization Operating costs and expenses (excluding depreciation and amortization) Operating costs and expenses (excluding depreciation and amortization) Operating costs and expenses (excluding depreciation and amortization) Depreciation Depreciation, Total Adjustment for Amortization Amortization Amortization of Intangible Assets, Total Other intangible assets, Accumulated Amortization Costs and Expenses, Total Costs and expenses, total Costs and expenses, total Operating income Operating Income (Loss) Operating income Operating income (loss) Other Income (Expense): Interest expense Interest expense Interest Interest Expense, Total Investment income (loss), net ' Investment income (loss), net Investment income (loss), net Equity in net income (losses) of investees, net Equity in net (income) losses of investees, net Equity in net income (losses) of investees, net Income (Loss) from Equity Method Investments, Total Other Nonoperating Income Expense Other income (expense) Other income (expense) Other Nonoperating Income (Expense), Total Other income (expense), net Nonoperating income (Expense), Total Nonoperating income (expense) Sum of operating profit and nonoperating income (expense) before income taxes, extraordinary items, cumulative effects of changes in accounting principles, and noncontrolling interest. Income Loss From Continuing Operations Before Income Taxes Income before income taxes Income before income taxes Income (loss) before income taxes Income tax expense Income tax expense Income taxes Income tax expense Income tax expense Net income from consolidated operations Net income from consolidated operations Net income (loss) from consolidated operations Net (income) loss attributable to noncontrolling interests Net (income) loss attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest, Total Net income attributable to Comcast Corporation Net income attributable to Comcast Corporation Net income (loss) attributable to Comcast Corporation Basic earnings per common share attributable to Comcast Corporation shareholders Earnings Per Share, Basic, Total Diluted earnings per common share attributable to Comcast Corporation shareholders Earnings Per Share, Diluted, Total Dividends declared per common share attributable to Comcast Corporation shareholders Dividend per share Condensed Consolidated Statement of Comprehensive Income Unrealized gains (losses) on marketable securities, net of deferred taxes of $0 and $0 Unrealized gains (losses) on marketable securities Unrealized gains (losses) on marketable securities, net of deferred taxes of $(3) and $ - Other Comprehensive Income, Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Deferred gains (losses) on cash flow hedges, net of deferred taxes of $(6) and $ - Reclassification adjustments for losses (gains) included in net income, net of deferred taxes of $(1) and $(12) Realized (gains) losses on marketable securities, net of deferred taxes of $4 and $ - Other Comprehensive Income, Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax Realized (gains) losses on cash flow hedges, net of deferred taxes of $7 and $(1) Employee benefit obligations, net of deferred taxes of $ 0 and $- Unrecognized gains (losses) on employee benefit obligations Other Comprehensive Income, Defined Benefit Plans Adjustment, Net of Tax, Total Employee benefit obligations, net of deferred taxes of $(2) and $ - Cumulative translation adjustments Currency translation adjustments Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total Comprehensive income Comprehensive income from consolidated operations Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Other comprehensive (income) loss attributable to noncontrolling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest, Total Comprehensive income attributable to Comcast Corporation Comprehensive income attributable to Comcast Corporation Unrealized gains (losses) on marketable securities, deferred taxes Other Comprehensive Income, Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Deferred gains (losses) on cash flow hedges, deferred taxes Realized (gains) losses on marketable securities, deferred taxes Other Comprehensive Income, Reclassification Adjustment on Derivatives Included in Net Income, Tax Realized (gains) losses on cash flow hedges, deferred taxes Employee benefit obligations, deferred taxes Employee benefit obligations, deferred taxes Other Comprehensive Income, Defined Benefit Plans, Tax, Total Condensed Consolidated Statement of Cash Flows Net cash provided by (used in) operating activities Net cash provided by operating activities Net cash provided by operating activities Investing Activities Capital expenditures Capital expenditures Capital Expenditures Payments to Acquire Property, Plant, and Equipment, Total Cash paid for intangible assets Cash paid for intangible assets Cash paid for intangible assets Cash paid for intangible assets Acquisitions, net of cash acquired Acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired, Total Proceeds from sales of investments Proceeds from Sale, Maturity and Collections of Investments, Total Purchases of investments Purchases of investments Payments to Acquire Investments, Total Other Other Net cash provided by (used in) investing activities Net cash provided by (used in) investing activities Financing Activities Proceeds From Repayments Of Short Term Debt Proceeds from (repayments of) short-term borrowings, net Proceeds from (Repayments of) Short-term Debt, Total Proceeds From Other Debt Proceeds from borrowings Repurchases and repayments of debt Repurchases and repayments of debt Debt Repayments and Repurchases Repayments of debt Repurchases of common stock Repurchases of common stock Aggregate consideration Dividends paid Dividends paid Payments of Dividends, Total Minority Interest Decrease From Distributions To Noncontrolling Interest Holders Distributions to noncontrolling interests Proceeds From Payments For Other Financing Activities Other Other Other Net cash provided by (used in) financing activities Net cash provided by (used in) financing activities Increase (decrease) in cash and cash equivalents Increase (decrease) in cash and cash equivalents Condensed Consolidated Statement of Changes in Equity Statement, Equity Components [Axis] Equity Component [Domain] Redeemable Non-controlling Interests [Member] Redeemable Noncontrolling Interests [Member] Additional Paid-In Capital [Member] Retained Earnings [Member] Treasury Stock at Cost [Member] Accumulated Other Comprehensive Income (Loss) [Member] Noncontrolling Interests [Member] Stock compensation plans Repurchase and retirement of common stock Repurchase and retirement of common stock Repurchase and retirement of common stock Employee stock purchase plan Dividends declared Dividends declared Amount Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Total Sale (purchase) of subsidiary shares to (from) noncontrolling interests, net Noncontrolling Interest, Period Increase (Decrease), Total Noncontrolling Interest Increase Decrease Related To Acquisition Noncontrolling Interest Increase Decrease Related To Acquisition NBCUniversal transaction Contributions from and (distributions to) noncontrolling interests. Contributions From And Distributions To Noncontrolling Interests Contributions from (distributions to) noncontrolling interests Profit or loss as represented on the statement of changes in equity. Equity Profit Loss Net income (loss) Condensed Consolidated Financial Statements [Abstract] Condensed Consolidated Financial Statements Organization and Business Condensed Consolidated Financial Statements Summary of Significant Accounting Policies Summary of Significant Accounting Policies Summary of Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Summary of Significant Accounting Policies Earnings Per Share Earnings Per Share [Text Block] Earnings Per Share Acquisitions And Other Significant Events Abstract Acquisitions and Other Significant Events Business Combination Disclosure Text block Acquisitions and Other Significant Events Film and Television Costs [Abstract] Film and Television Costs Film and Television costs Disclosure [Text Block] Film and Television costs Disclosure [Text Block] Film and Television Costs Investments Includes all investments held by the company under the equity, cost and the fair value methods. Represents total on the balance sheet. Includes the components of investment income (loss), net. Investments [Text Block] Investments Good will Goodwill and Other Intangible Assets Goodwill And Intangible Assets Disclosure Text Block Goodwill and Other Intangible Assets Long-Term Debt Long-Term Debt [Text Block] Long-Term Debt Derivative Financial Instruments [Abstract] Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Financial Instruments Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Fair Value Measurements Noncontrolling Interests Noncontrolling Interests Noncontrolling Interest Disclosure [Text Block] Noncontrolling Interests Postretirement, Pension and Other Employee Benefit Plans Postretirement, Pension and Other Employee Benefit Plans text block Postretirement, Pension and Other Employee Benefit Plans Share-Based Compensation Disclosure of Compensation Related Costs, Share-Based Payments Share-Based Compensation Supplemental Financial Information Supplemental Financial Information [Text Block] Supplemental Financial Information [Text Block] Supplemental Financial Information Receivables Receivables Monetization Receivables Monetization [Text Block] Receivables Monetization [Text Block] Receivables Monetization Commitments And Contingencies Abstract Commitments and Contingencies Commitments And Contingencies Disclosure Text Block Commitments and Contingencies Financial Data By Business Segment Abstract Financial Data by Business Segment Segment Reporting Disclosure [Text Block] Financial Data by Business Segment Condensed Consolidating Financial Information [Abstract] Condensed Consolidating Financial Information Schedule Of Condensed Financial Statements TextBlock Condensed Consolidating Financial Information Use of estimates policy Use of estimates policy [Text Block] Use of Estimates 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. Film and Television Costs [Policy Text Block] Film and Television Costs Revenue Recognition, Policy [Text Block] Revenue Recognition Foreign Currency Transactions and Translations Policy [Text Block] Foreign Currency Translation Reclassifications of prior year amounts Reclassifications Of Prior Year Amounts [Policy TextBlock] Reclassifications Derivatives, Policy Derivatives Foreign Currency Derivative Financial Instruments Computation of Diluted EPS Earnings Per Share Schedule Of Acquisition Related Expenses Included In Consolidated Statement Of Income [Table Text Block] Schedule Of Acquisition Related Expenses Included In Consolidated Statement Of Income [Table Text Block] Total Operating Costs and Expenses Schedule of Purchase Price Allocation [Table Text Block] Schedule of Purchase Price Allocation [Table Text Block] Fair Value of Identifiable Net Assets Acquired Business Acquisition, Pro Forma Information [Text Block] Unaudited Pro Forma Information Schedule of Film and Television Costs [Text Block] Schedule of Film and Television Costs [Text Block] Film and Television Costs Investment summary. Investment Summary Text Block Investment Summary Components of Investment Income (Loss), Net Components Of Investment Income Loss Net Text Block Investment Income (Loss), Net Schedule of Goodwill Schedule of Goodwill Carrying Amount of Goodwill Intangible Assets Disclosure [Text Block] Other Intangible Assets Schedule of Long-term Debt Instruments [Text Block] Schedule of Long-Term Debt in Connection with NBCUniversal Transaction Schedule of the location and amount of gains and losses reported in the statement of operations on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges. Amount Of Gain Loss Recognized In Income Fair Value Hedges [Text Block] Amount of Gain (Loss) Recognized in Income-Fair Value Hedges Pretax Amount Of Gain Loss Recognized In Accumulated Other Comprehensive Income Cash Flow Hedges [Text Block] Pretax Amount Of Gain Loss Recognized In Accumulated Other Comprehensive Income Cash Flow Hedges [Text Block] Pretax Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income - Cash Flow Hedges Schedule of the location and amount of gains and losses reported in the statement of financial performance on nondesignated derivative financial instruments. Amount Of Gain Loss Recognized In Income Nondesignated [Text Block] Amount of Gain (Loss) Recognized in Income - Nondesignated Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis [Table Text Block] Fair Value Assets and Liabilities Measured on Recurring Basis Schedule Summarizing Changes In Equity Resulting From Net Income Attributable To Parent And Transfers To Or From Noncontrolling Interests [Text Block] Changes in equity resulting from net income attributable to parent and transfers to or from noncontrolling interests [Text Block] Schedule Summarizing Changes in Equity Resulting from Net Income Attributable to Parent and Transfers to or from Noncontrolling Interests Schedule, table or text reflecting pension and other postretirement benefit available to all eligible employees. Disclosure also typically includes the amount of related compensation expense recognized during the reporting period and the carrying amount as of the balance sheet date of the related liability. Condensed Information On Our Postretirement And Pension Benefit Plans Text Block Condensed Information on Our Postretirement and Pension Benefit Plans Recognized share-based compensation expense Recognized Share-Based Compensation Expense Text Block Recognized Share-Based Compensation Expense