| Investments In Available-For-Sale Securities And Other Cost Investments (Unrealized Holding Gains And Losses) (Details) (USD $) In Millions, unless otherwise specified | 9 Months Ended | ||||
|---|---|---|---|---|---|
| Sep. 30, 2013
 Equity Securities [Member] | Dec. 31, 2012
 Equity Securities [Member] | Sep. 30, 2013
 Debt Securities [Member] | Dec. 31, 2012
 Debt Securities [Member] | Sep. 30, 2013
 SIRIUS XM [Member] | |
| Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax | $ 40 | ||||
| Gross unrealized holding gains | 7 | 2 | 1 | 37 | |
| Gross unrealized holding losses | $ 0 | $ 0 | $ 0 | $ 0 | 
| X | ||||||||||
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- Definition This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition This item represents the gross unrealized losses for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities. No definition available. 
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