Quarterly report pursuant to Section 13 or 15(d)

Assets and Liabilities Measured at Fair Value (Schedule of Assets and Liabilities) (Details)

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Assets and Liabilities Measured at Fair Value (Schedule of Assets and Liabilities) (Details) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents $ 253,860 $ 570,526
Equity securities 1,667,642 1,800,208
Investment in Liberty Broadband 3,657,407 3,634,786
Indemnification obligation 252,538 0
Variable forward    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Variable forward 86,065 94,807
Quoted prices in active markets for identical assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents 253,860 570,526
Equity securities 1,667,642 1,800,208
Investment in Liberty Broadband 3,657,407 3,634,786
Indemnification obligation 0 0
Quoted prices in active markets for identical assets (Level 1) | Variable forward    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Variable forward 0 0
Significant other observable inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents 0 0
Equity securities 0 0
Investment in Liberty Broadband 0 0
Indemnification obligation 252,538 0
Significant other observable inputs (Level 2) | Variable forward    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Variable forward $ 86,065 $ 94,807