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, 2019
Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents $ 351,076 $ 384,071
Equity securities 1,862,553 1,529,901
Investment in Liberty Broadband 3,915,632 3,074,373
Indemnification obligation 110,317 78,522
Exchangeable senior debentures 521,376 462,336
Exchangeable senior debentures    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Exchangeable senior debentures 521,376 462,336
Variable forward    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Variable forward 91,484 20,340
Quoted prices in active markets for identical assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash equivalents 351,076 384,071
Equity securities 1,862,553 1,529,901
Investment in Liberty Broadband 3,915,632 3,074,373
Indemnification obligation 0 0
Quoted prices in active markets for identical assets (Level 1) | Exchangeable senior debentures    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Exchangeable senior debentures 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 110,317 78,522
Significant other observable inputs (Level 2) | Exchangeable senior debentures    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Exchangeable senior debentures 521,376 462,336
Significant other observable inputs (Level 2) | Variable forward    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Variable forward $ 91,484 $ 20,340