Quarterly report pursuant to Section 13 or 15(d)

Tracking Stock (Details)

v2.4.0.6
Tracking Stock (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Sep. 30, 2012
Mar. 31, 2013
Dec. 31, 2012
Sep. 30, 2011
Dec. 31, 2010
Tracking Stock [Abstract]          
Stockholders' Equity Note, Stock Split, Conversion Ratio 0.05        
Cash and Cash Equivalents, at Carrying Value   $ 1,370 $ 2,660 $ 794 $ 847
Ventures Group [Member]
         
Tracking Stock [Abstract]          
Cash and Cash Equivalents, at Carrying Value   783 1,961 0 0
Interactive Group [Member]
         
Tracking Stock [Abstract]          
Cash and Cash Equivalents, at Carrying Value   $ 587 $ 699 $ 794 $ 847