Quarterly report pursuant to Section 13 or 15(d)

Investments in Affiliates Accounted for Using the Equity Method (Investment in Liberty Broadband) (Details)

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Investments in Affiliates Accounted for Using the Equity Method (Investment in Liberty Broadband) (Details)
$ / shares in Units, $ in Thousands
May 18, 2016
USD ($)
Jun. 30, 2018
USD ($)
Dec. 31, 2017
USD ($)
May 31, 2015
$ / shares
Schedule of Equity Method Investments [Line Items]        
Investments accounted for using the equity method   $ 121,880 $ 114,655  
Series A common stock | Charter        
Schedule of Equity Method Investments [Line Items]        
Shares, exchange ratio 1      
Liberty Broadband        
Schedule of Equity Method Investments [Line Items]        
Investments accounted for using the equity method   $ 3,231,869 3,634,786  
Percentage ownership   23.50%    
Liberty Broadband | Series C Non-voting Shares        
Schedule of Equity Method Investments [Line Items]        
Investments accounted for using the equity method $ 2,400,000      
Liberty Broadband | Series C Common Stock        
Schedule of Equity Method Investments [Line Items]        
Per share price of stock purchased (in dollars per share) | $ / shares       $ 56.23
Charter | Liberty Broadband        
Schedule of Equity Method Investments [Line Items]        
Investments accounted for using the equity method   $ 11,891,637 $ 11,835,613  
Payments to acquire investments $ 5,000,000