Quarterly report pursuant to Section 13 or 15(d)

Investments In Available-For-Sale Securities And Other Cost Investments (Narrative) (Details)

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Investments In Available-For-Sale Securities And Other Cost Investments (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 1 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Jan. 18, 2013
SIRIUS XM [Member]
Purchase of shares in equity method investee     50.0
Payments to Acquire Investments $ 18 $ 2