v2.4.0.6

Consolidated Statement of Changes in Equity (USD $) In Millions | Total | Redeemable Noncontrolling Interests [Member] | Class A Common Stock [Member] | ClassA Special Common Stock [Member] | Class B Common Stock [Member] | Additional Paid-In Capital [Member] | Retained Earnings [Member] | Treasury Stock at Cost [Member] | Accumulated Other Comprehensive Income (Loss) [Member] | Noncontrolling Interests [Member]
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Beginning Balance at Dec. 31, 2010 | $ 44,434 | $ 143 | $ 24 | $ 8 | $ 0 | $ 39,780 | $ 12,158 | $ (7,517) | $ (99) | $ 80
Stock compensation plans | 276 |  | 1 |  |  | 310 | (35) |  |  |
Repurchase and retirement of common stock | (1,050) |  |  | (1) |  | (514) | (535) |  |  |
Employee stock purchase plan | 33 |  |  |  |  | 33 |  |  |  |
Dividends declared | (621) |  |  |  |  |  | (621) |  |  |
Other comprehensive income (loss) | (6) |  |  |  |  |  |  |  | (6) |
NBCUniversal transaction | 1,880 | 15,166 |  |  |  | 1,692 |  |  |  | 188
Contributions from (distributions to) noncontrolling interests | (85) | (162) |  |  |  |  |  |  |  | (85)
Net income (loss) | 2,044 | 362 |  |  |  |  | 1,965 |  |  | 79
Ending Balance at Jun. 30, 2011 | 46,905 | 15,509 | 25 | 7 | 0 | 41,301 | 12,932 | (7,517) | (105) | 262
Beginning Balance at Dec. 31, 2011 | 47,655 | 16,014 | 25 | 7 | 0 | 40,940 | 13,971 | (7,517) | (152) | 381
Stock compensation plans | 234 |  |  |  |  | 361 | (127) |  |  |
Repurchase and retirement of common stock | (1,500) |  |  | (1) |  | (583) | (916) |  |  |
Employee stock purchase plan | 41 |  |  |  |  | 41 |  |  |  |
Dividends declared | (874) |  |  |  |  |  | (874) |  |  |
Other comprehensive income (loss) | (18) | (8) |  |  |  |  |  |  | (18) |
Contributions from (distributions to) noncontrolling interests | (85) | (132) |  |  |  |  |  |  |  | (85)
Other | 95 | (44) |  |  |  | 2 |  |  |  | 93
Net income (loss) | 2,631 | 449 |  |  |  |  | 2,572 |  |  | 59
Ending Balance at Jun. 30, 2012 | $ 48,179 | $ 16,279 | $ 25 | $ 6 | $ 0 | $ 40,761 | $ 14,626 | $ (7,517) | $ (170) | $ 448

X
- Definition Contributions from and (distributions to) noncontrolling interests. + References No definition available. + Details
Name: | cmcsa_ContributionsFromAndDistributionsToNoncontrollingInterests
Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Profit or loss as represented on the statement of changes in equity. + References No definition available. + Details
Name: | cmcsa_EquityProfitLoss
Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Noncontrolling interest increase decrease related to an acquisition. + References No definition available. + Details
Name: | cmcsa_NoncontrollingInterestIncreaseDecreaseRelatedToAcquisition
Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Equity impact of common stock cash dividends declared by an entity during the period. This element includes paid and unpaid dividends declared during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770 + Details
Name: | us-gaap_DividendsCommonStockCash
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents Other Comprehensive Income or Loss, Net of Tax, for the period. Includes deferred gains or losses on qualifying hedges, unrealized holding gains or losses on available-for-sale securities, minimum pension liability, and cumulative translation adjustment. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 130 -Paragraph 22, 23, 24, 25 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e599-108580 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 31 -Article 5 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(3) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total of Stockholders' Equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity including portions attributable to both the parent and noncontrolling interests (previously referred to as minority interest), if any. The entity including portions attributable to the parent and noncontrolling interests is sometimes referred to as the economic entity. This excludes temporary equity and is sometimes called permanent equity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 16 -URI http://asc.fasb.org/extlink&oid=6921628&loc=SL4568740-111683 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4I -URI http://asc.fasb.org/extlink&oid=6922042&loc=SL4590271-111686 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Name Accounting Research Bulletin (ARB) -Publisher AICPA -Number 51 -Paragraph 26 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A3 -Appendix A Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 25 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6921628&loc=SL4568447-111683 + Details
Name: | us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This element represents movements included in the statement of changes in stockholders' equity which are not separately disclosed or provided for elsewhere in the taxonomy. + References No definition available. + Details
Name: | us-gaap_StockholdersEquityOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Aggregate change in value for stock issued during the period as a result of employee stock purchase plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30, 31 -Article 5 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30, 31 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30, 31 -Article 5 + Details
Name: | us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration