XML 79 R65.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Related Party Transactions (Condensed Consolidated Statement of Income) (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Related Party Transaction [Line Items] |  |  |  |
Revenue | $ 21,735 | $ 21,286 | $ 44,526 | $ 41,873
Total costs and expenses | (16,721) | (16,718) | (34,867) | (32,763)
NBCUniversal Media LLC [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Revenue | 8,313 | 8,318 | 17,843 | 16,171
Total costs and expenses | (6,706) | (6,764) | (14,461) | (13,106)
Comcast and Consolidated Subsidiaries [Member] | NBCUniversal Media LLC [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Revenue | 480 | 460 | 1,074 | 919
Total costs and expenses | (42) | (49) | (103) | (110)
Interest expense and investment and other income (loss), net | $ (20) | $ (28) | $ (43) | $ (47)

X
- Definition Represents the intercompany transactions with ultimate parent, which are included in interest expense and investment and other income (loss), net. + References No definition available. + Details
Name: | cmcsa_OtherIncomeExpenseRelatedParty
Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Total costs of sales and operating expenses for the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_CostsAndExpenses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 + Details
Name: | us-gaap_Revenues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=cmcsa_NBCUniversalMediaLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=cmcsa_ComcastAndConsolidatedSubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |