Quarterly report pursuant to Section 13 or 15(d)

Investments in Debt and Equity Securities - Summary (Details)

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Investments in Debt and Equity Securities - Summary (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Transaction details [Line Items]    
Consolidated Liberty $ 1,573 $ 1,114
Liberty Sirius XM Group    
Transaction details [Line Items]    
Debt securities 1,031 580
Consolidated Liberty 1,031  
Liberty Sirius XM Group | Pandora | Debt Securities    
Transaction details [Line Items]    
Debt securities 512 480
Liberty Sirius XM Group | iHeart    
Transaction details [Line Items]    
Principal amount of debt securities acquired during period 522  
Payments to acquire debt securities 389  
Debt security, principal balance 660  
Liberty Sirius XM Group | iHeart | Debt Securities    
Transaction details [Line Items]    
Debt securities 519 100
Braves Group    
Transaction details [Line Items]    
Other equity securities 8 8
Consolidated Liberty 8  
Braves Group | Other AFS Securities | Equity Securities    
Transaction details [Line Items]    
Other equity securities 8 8
Formula One Group    
Transaction details [Line Items]    
Equity securities 534 526
Consolidated Liberty 534  
Formula One Group | Time Warner Inc | Equity Securities    
Transaction details [Line Items]    
Equity securities 402 389
Formula One Group | Other AFS Securities | Equity Securities    
Transaction details [Line Items]    
Equity securities $ 132 $ 137