v3.5.0.2

Commitments and Contingencies (Insurance Obligations) (Details) $ in Millions | 3 Months Ended
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Jun. 30, 2016 USD ($)
Expense related to the settlement of insurance obligations | $ 116

X
- Definition Expense related to the settlement of insurance obligations recorded in other operating and administrative expenses + References No definition available. + Details
Name: | cmcsa_ExpenseRelatedToTheSettlementOfInsuranceObligations
Namespace Prefix: | cmcsa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration