v2.4.1.9

Income Taxes (Federal Statutory) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Federal tax at statutory rate | $ 4,363 us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate | $ 3,890 us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate | $ 4,063 us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate
State income taxes, net of federal benefit | 329 us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes | 319 us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes | 178 us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes
Foreign income taxes, net of federal credit | 0 us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential | 15 us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential | 92 us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential
Nontaxable income attributable to noncontrolling interests | (62)us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense | (103)us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense | (620)us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense
Other adjustments | (114)us-gaap_IncomeTaxReconciliationOtherAdjustments | (313)us-gaap_IncomeTaxReconciliationOtherAdjustments | (106)us-gaap_IncomeTaxReconciliationOtherAdjustments
Income tax expense | 3,873 us-gaap_IncomeTaxExpenseBenefit | 3,980 us-gaap_IncomeTaxExpenseBenefit | 3,744 us-gaap_IncomeTaxExpenseBenefit
Uncertain And Effectively Settled Tax Positions, Net [Member] |  |  |
Other adjustments | (408)us-gaap_IncomeTaxReconciliationOtherAdjustments / cmcsa_TaxAdjustmentsAxis = cmcsa_UncertainAndEffectivelySettledTaxPositionsNetMember | 58 us-gaap_IncomeTaxReconciliationOtherAdjustments / cmcsa_TaxAdjustmentsAxis = cmcsa_UncertainAndEffectivelySettledTaxPositionsNetMember | 114 us-gaap_IncomeTaxReconciliationOtherAdjustments / cmcsa_TaxAdjustmentsAxis = cmcsa_UncertainAndEffectivelySettledTaxPositionsNetMember
Accrued Interest On Uncertain And Effectively Settled Tax Positions Net [Member] |  |  |
Other adjustments | $ (235)us-gaap_IncomeTaxReconciliationOtherAdjustments / cmcsa_TaxAdjustmentsAxis = cmcsa_AccruedInterestOnUncertainAndEffectivelySettledTaxPositionsNetMember | $ 114 us-gaap_IncomeTaxReconciliationOtherAdjustments / cmcsa_TaxAdjustmentsAxis = cmcsa_AccruedInterestOnUncertainAndEffectivelySettledTaxPositionsNetMember | $ 23 us-gaap_IncomeTaxReconciliationOtherAdjustments / cmcsa_TaxAdjustmentsAxis = cmcsa_AccruedInterestOnUncertainAndEffectivelySettledTaxPositionsNetMember

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- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Article 4 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Income Tax Expense (or Benefit) -URI http://asc.fasb.org/extlink&oid=6515339 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319 + Details
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- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to foreign income tax expense (benefit). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Subparagraph 1 -Article 4 + Details
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- Definition The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Subparagraph 2 -Article 4 + Details
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- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to noncontrolling interest income (loss) exempt from income taxes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319 + Details
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- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to other adjustments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319 + Details
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