v2.4.0.6

Condensed Consolidating Financial Information (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended
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Jun. 30, 2012
Holding company ownership in subsidiaries | 100.00%
Comcast Holdings' ZONES due October 2029 [Member] |
Amount of unconditional guarantee of principal amount outstanding of Comcast Holdings | 185
Debt Instrument, Maturity Date, Description | 2029
Comcast Holdings' 10 5/8% senior subordinated debentures due 2012 [Member] |
Current principal balance | 202
Interest rate | 10.625%
Debt Instrument, Maturity Date, Description | 2012
Comcast Holdings' ZONES due November 2029 [Member] |
Current principal balance | 62
Debt Instrument, Maturity Date, Description | 2029

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