Quarterly report pursuant to Section 13 or 15(d)

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

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Investments In Available-For-Sale Securities And Other Cost Investments (Details)
$ / shares in Units, $ in Millions
3 Months Ended 9 Months Ended
Dec. 31, 2017
director
Sep. 22, 2017
$ / shares
shares
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     $ 1,120   $ 1,120   $ 1,309
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax     0   0   0
Payments to Acquire Investments         760 $ 762  
Unrealized Gain (Loss) on Securities     18 $ 7 (43) (33)  
Pandora | SIRIUS XM              
Transaction details [Line Items]              
Payments to Acquire Investments         480    
Ownership Interest In Investee   19.00%          
Ownership percentage on an as-converted basis   16.00%          
Convertible Preferred Stock, Price Per Share | $ / shares   $ 10.50          
Convertible Preferred Stock, Shares Issued upon Conversion | shares   95.2381          
Preferred Stock, Dividend Rate, Percentage   6.00%          
Cost Method Investment Minimum Threshold Percentage Approved Issuance   19.99          
Cost Method Investment Maximum Percentage Threshold For Conversion Of Preferred Shares   19.99%          
Cost Method Investment, Number of Directors Designated | director 3            
Cost Method Investment, Number of Directors Designated, Chairman | director 1            
Unrealized Gain (Loss) on Securities     62   62    
Pandora | SIRIUS XM | Minimum              
Transaction details [Line Items]              
Cost Method Investment, Minimum Ownerships Percentage for Director Designation, Converted Basis 50.00%            
Cost Method Investment, Minimum Ownership Percentage for Designation of Two Directors, Converted Basis 75.00%            
Liberty Sirius XM Group              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     552   552    
Payments to Acquire Investments         750    
Unrealized Gain (Loss) on Securities     62   62    
Liberty Sirius XM Group | Pandora | Fair Value Option Securities              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     552   552    
Braves Group              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     8   8   8
Payments to Acquire Investments         2 13  
Braves Group | Other equity securities | AFS and cost method investments              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     8   8   8
Formula One Group              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     560   560   1,301
Payments to Acquire Investments         8 749  
Unrealized Gain (Loss) on Securities     (44) $ 7 (105) $ (33)  
Formula One Group | Fair Value Option Securities              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     502   502   489
Formula One Group | AFS and cost method investments              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     58   58   812
Formula One Group | Time Warner Inc | Fair Value Option Securities              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     436   436   411
Formula One Group | Viacom, Inc. | Fair Value Option Securities              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     52   52   65
Formula One Group | Formula 1 | AFS and cost method investments              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments             759
Formula One Group | Other equity securities | Fair Value Option Securities              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     14   14   13
Formula One Group | Other AFS Equity Securities | AFS and cost method investments              
Transaction details [Line Items]              
Investments in available-for-sale securities and other cost investments     $ 58   $ 58   $ 53