| Segment Information (Tables)
 | 6 Months Ended | 
| Jun. 30, 2021 | 
|---|
| Segment Information |  | 
| Schedule of performance measures |  
|  |  |  |  |  |  |  |  |  |  |  |  |  
|  |  | Three months ended   |  | Six months ended  |  |  
|  |  | June 30,  |  | June 30,  |  |  
|  |  | 2021 |      | 2020 |  | 2021 |      | 2020 |  |  |  |  
|  |  | amounts in thousands |  |  
| GCI Holdings |  |  |    |   |    |  |  |    |   |    |  |  
| Consumer Revenue |  |  |    |   |    |  |  |    |   |    |  |  
| Wireless |  | $ |  32,343 |  |  — |  |  |  64,314 |  |  — |  |  
| Data |  |   |  52,661 |  |  — |  |  |  104,886 |  |  — |  |  
| Video |  |   |  18,704 |  |  — |  |  |  37,633 |  |  — |  |  
| Voice |  |   |  3,681 |  |  — |  |  |  7,235 |  |  — |  |  
| Business Revenue |  |   |  |  |  |  |  |  |  |  |  |  
| Wireless |  |   |  18,410 |  |  — |  |  |  37,311 |  |  — |  |  
| Data |  |   |  85,748 |  |  — |  |  |  176,034 |  |  — |  |  
| Video |  |   |  880 |  |  — |  |  |  1,682 |  |  — |  |  
| Voice |  |   |  6,008 |  |  — |  |  |  12,156 |  |  — |  |  
| Lease, grant, and revenue from subsidies |  |   |  19,421 |  |  — |  |  |  38,821 |  |  — |  |  
| Total GCI Holdings |  |  |  237,856 |  |  — |  |  |  480,072 |  |  — |  |  
| Corporate and other |  |  |  4,428 |  |  4,114 |  |  |  8,746 |  |  8,218 |  |  
| Total |  | $ |  242,284 |   |  4,114 |  |  |  488,818 |   |  8,218 |  |  | 
| Schedule of segment reporting information |  
|  |  |  |  |  |  |  |  |  |  |  |  
|  |  | Three months ended  June 30,  |  | Six months ended June 30,  |  
|  |  | 2021 |  | 2020 |  | 2021 |  | 2020 |  |  |  
|  |  | amounts in thousands |  
| GCI Holdings |      | $ |  88,656 |      |  — |      |  |  184,715 |  |  — |  
| Charter |  |   |  5,029,000 |  |  4,487,000 |  |   |  9,672,000 |  |  8,876,000 |  
| Corporate and other |  |   |  (13,309) |  |  (7,407) |  |   |  (26,615) |  |  (12,388) |  
|  |  |   |  5,104,347 |  |  4,479,593 |  |   |  9,830,100 |  |  8,863,612 |  
| Eliminate equity method affiliate |  |   |  (5,029,000) |  |  (4,487,000) |  |   |  (9,672,000) |  |  (8,876,000) |  
| Consolidated Liberty Broadband |  | $ |  75,347 |  |  (7,407) |  |  |  158,100 |  |  (12,388) |   
|  |  |  |  |  |  |  |  |  |  
|  |  | June 30, 2021 |   |  
|  |  | Total |  | Investments |  | Capital |   |  
|  |  | assets |  | in affiliates |  | expenditures |   |  |  |  
|  |  | amounts in thousands |   |  
| GCI Holdings |      | $ |  3,527,081 |      |  362 |      |  50,080 |  |  
| Charter |  |   |  144,026,000 |   | — |   |  3,702,000 |  |  
| Corporate and other |  |   |  15,247,976 |   |  14,947,692 |   |  19 |  |  
|  |  |   |  162,801,057 |   |  14,948,054 |   |  3,752,099 |  |  
| Eliminate equity method affiliate |  |   |  (144,026,000) |   |  — |   |  (3,702,000) |  |  
| Consolidated Liberty Broadband |  | $ |  18,775,057 |   |  14,948,054 |   |  50,099 |  |  | 
| Schedule of reconciliation of segment Adjusted OIBDA to earnings (loss) before income taxes |  
|  |  |  |  |  |  |  |  |  |  |  |  
|  |  | Three months ended   |  | Six months ended  |   |  
|  |  | June 30,  |  | June 30,  |   |  
|  |  | 2021 |  | 2020 |  | 2021 |      | 2020 |   |  |  |  
|  |  |  | amounts in thousands |   |  
| Adjusted OIBDA |      | $ |  75,347 |      |  (7,407) |      |  158,100 |      |  (12,388) |  |  
| Stock-based compensation |  |   |  (10,565) |  |  (1,933) |  |  (20,435) |   |  (3,734) |  |  
| Depreciation and amortization |  |   |  (66,874) |  |  (492) |  |  (130,636) |   |  (985) |  |  
| Litigation settlement |  |  |  — |  |  — |  |  (110,000) |  |  — |  |  
| Operating income (loss) |  |  |  (2,092) |  |  (9,832) |  |  (102,971) |  |  (17,107) |  |  
| Interest expense |  |  |  (28,734) |  |  (5,131) |  |  (61,877) |   |  (10,992) |  |  
| Share of earnings (loss) of affiliates, net |  |   |  248,848 |  |  158,128 |  |  437,827 |   |  219,810 |  |  
| Gain (loss) on dilution of investment in affiliate |  |   |  (14,538) |  |  (46,001) |  |  (96,753) |   |  (105,326) |  |  
| Realized and unrealized gains (losses) on financial instruments, net |  |   |  (125,064) |  |  — |  |  (25,716) |   |  — |  |  
| Other, net |  |   |  22,720 |  |  28 |  |  14,594 |   |  191 |  |  
| Earnings (loss) before income taxes |  | $ |  101,140 |  |  97,192 |  |  165,104 |   |  86,576 |  |  |