Quarterly report pursuant to Section 13 or 15(d)

Tracking Stock (Details)

v2.4.0.8
Tracking Stock (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2012
Sep. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Jun. 30, 2012
Dec. 31, 2011
Sep. 30, 2011
Tracking Stock [Abstract]                
Stockholders' Equity Note, Stock Split, Conversion Ratio 0.05              
Cash and Cash Equivalents, at Carrying Value     $ 981 $ 981 $ 2,660 $ 1,793 $ 847 $ 1,793
Reattribution Of Cash Between Tracking Stocks   0            
Ventures Group [Member]
                
Tracking Stock [Abstract]                
Cash and Cash Equivalents, at Carrying Value     526   1,961 1,235 0  
Reattribution Of Cash Between Tracking Stocks   1,346            
Interactive Group [Member]
                
Tracking Stock [Abstract]                
Cash and Cash Equivalents, at Carrying Value     455   699 558 847  
Reattribution Of Cash Between Tracking Stocks   $ (1,346)