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
6 Months Ended
Jun. 30, 2018
Dec. 31, 2017
Transaction details [Line Items]    
Consolidated Liberty $ 1,429 $ 1,114
Liberty Sirius XM Group    
Transaction details [Line Items]    
Debt securities 1,103 580
Consolidated Liberty 1,103  
Liberty Sirius XM Group | Pandora | Debt Securities    
Transaction details [Line Items]    
Debt securities 598 480
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 505 100
Braves Group    
Transaction details [Line Items]    
Other equity securities 8 8
Consolidated Liberty 8  
Braves Group | Other Equity Securities | Equity Securities    
Transaction details [Line Items]    
Other equity securities 8 8
Formula One Group    
Transaction details [Line Items]    
Equity securities 318 526
Consolidated Liberty 318  
Formula One Group | AT&T | Equity Securities    
Transaction details [Line Items]    
Equity securities 196 389
Formula One Group | Other Equity Securities | Equity Securities    
Transaction details [Line Items]    
Equity securities $ 122 $ 137