v3.5.0.2

Share-Based Compensation (Narrative) (Details) $ / shares in Units, shares in Millions, $ in Millions | 6 Months Ended
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Jun. 30, 2016 USD ($) $ / shares shares
Number of stock options granted | shares | 20.7
Number of restricted share units granted | shares | 5.9
Weighted average fair value of stock options granted | $ / shares | $ 11.45
Weighted average fair value of restricted share units granted | $ / shares | $ 59.5
Restricted Share Units [Member] |
Unrecognized pretax compensation expense on nonvested awards | $ | $ 831
Stock Options [Member] |
Unrecognized pretax compensation expense on nonvested awards | $ | $ 448

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- Definition The weighted average fair value of restricted share units granted related to our annual management grant program. + References No definition available. + Details
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Namespace Prefix: | cmcsa_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

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- Definition The weighted average fair value of stock options granted related to our annual management grant program. + References No definition available. + Details
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Namespace Prefix: | cmcsa_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of restricted share units granted related to our annual management grant program. + References No definition available. + Details
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Namespace Prefix: | cmcsa_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of stock options granted related to our annual management grant program. + References No definition available. + Details
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Namespace Prefix: | cmcsa_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Details
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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |