XML 81 R67.htm IDEA: XBRL DOCUMENT v3.10.0.1

Commitments and Contingencies (Narrative) (Details) $ in Millions	Jun. 30, 2018 USD ($)
Redeemable Preferred Stock [Member] | Level 2 [Member]
Temporary Equity [Line Items]
Fair Value of Redeemable subsidiary preferred stock	$ 746

X

- Definition

Temporary Equity, Fair Value of our redeemable subsidiary preferred stock.

+ References

No definition available.

+ Details

Name:	cmcsa_TemporaryEquityFairValueOfRedeemableSubsidiaryPreferredStock
Namespace Prefix:	cmcsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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_TemporaryEquityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_RedeemablePreferredStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: