Information About the Company's Operating Segments (Tables)
   | 
9 Months Ended | 
Sep. 30, 2018  | 
| Segment Reporting [Abstract] | 
 
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| Reconciliation of Revenue from Segments to Consolidated | 
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   | 
Three Months Ended September 30,  | 
 
   | 
2018  | 
   | 
2017  | 
 
   | 
Revenue  | 
   | 
Adjusted OIBDA  | 
   | 
Revenue  | 
   | 
Adjusted OIBDA  | 
 
   | 
amounts in thousands  | 
 
GCI Holdings  | 
$  | 
205,047  | 
 
  | 
   | 
57,945  | 
 
  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
 
Liberty Broadband  | 
3,518  | 
 
  | 
   | 
(2,198  | 
)  | 
   | 
3,430  | 
 
  | 
   | 
(3,346  | 
)  | 
 
Corporate and other  | 
5,099  | 
 
  | 
   | 
(7,205  | 
)  | 
   | 
5,493  | 
 
  | 
   | 
(5,277  | 
)  | 
 
   | 
213,664  | 
 
  | 
   | 
48,542  | 
 
  | 
   | 
8,923  | 
 
  | 
   | 
(8,623  | 
)  | 
 
Eliminate Liberty Broadband  | 
(3,518  | 
)  | 
   | 
2,198  | 
 
  | 
   | 
(3,430  | 
)  | 
   | 
3,346  | 
 
  | 
 
   | 
$  | 
210,146  | 
 
  | 
   | 
50,740  | 
 
  | 
   | 
5,493  | 
 
  | 
   | 
(5,277  | 
)  | 
 
  
 
 
  
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   | 
Nine Months Ended September 30,  | 
 
   | 
2018  | 
   | 
2017  | 
 
   | 
Revenue  | 
   | 
Adjusted OIBDA  | 
   | 
Revenue  | 
   | 
Adjusted OIBDA  | 
 
   | 
amounts in thousands  | 
 
GCI Holdings  | 
$  | 
489,620  | 
 
  | 
   | 
156,608  | 
 
  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
 
Liberty Broadband  | 
18,680  | 
 
  | 
   | 
(414  | 
)  | 
   | 
9,643  | 
 
  | 
   | 
(12,262  | 
)  | 
 
Corporate and other  | 
15,220  | 
 
  | 
   | 
(20,256  | 
)  | 
   | 
15,639  | 
 
  | 
   | 
(20,071  | 
)  | 
 
   | 
523,520  | 
 
  | 
   | 
135,938  | 
 
  | 
   | 
25,282  | 
 
  | 
   | 
(32,333  | 
)  | 
 
Eliminate Liberty Broadband  | 
(18,680  | 
)  | 
   | 
414  | 
 
  | 
   | 
(9,643  | 
)  | 
   | 
12,262  | 
 
  | 
 
   | 
$  | 
504,840  | 
 
  | 
   | 
136,352  | 
 
  | 
   | 
15,639  | 
 
  | 
   | 
(20,071  | 
)  | 
 
  
 
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| Reconciliation of Assets from Segment to Consolidated | 
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   | 
   | 
September 30, 2018  | 
 
   | 
   | 
Total  | 
   | 
Investments  | 
   | 
Capital  | 
 
   | 
   | 
assets  | 
   | 
in affiliates  | 
   | 
expenditures  | 
 
   | 
   | 
amounts in thousands  | 
 
GCI Holdings  | 
   | 
$  | 
3,561,569  | 
 
  | 
   | 
—  | 
 
  | 
   | 
86,977  | 
 
  | 
 
Liberty Broadband  | 
   | 
12,082,674  | 
 
  | 
   | 
11,977,368  | 
 
  | 
   | 
35  | 
 
  | 
 
Corporate and other  | 
   | 
6,318,888  | 
 
  | 
   | 
174,134  | 
 
  | 
   | 
2,399  | 
 
  | 
 
   | 
   | 
21,963,131  | 
 
  | 
   | 
12,151,502  | 
 
  | 
   | 
89,411  | 
 
  | 
 
Eliminate Liberty Broadband  | 
   | 
(12,082,674  | 
)  | 
   | 
(11,977,368  | 
)  | 
   | 
(35  | 
)  | 
 
Consolidated  | 
   | 
$  | 
9,880,457  | 
 
  | 
   | 
174,134  | 
 
  | 
   | 
89,376  | 
 
  | 
 
  
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| Reconciliation of Adjusted OIBDA to Operating Income and Earnings (Loss) from Continuing Operations | 
The following table provides a reconciliation of segment Adjusted OIBDA to operating income and earnings (loss) from continuing operations before income taxes: 
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   | 
Three Months Ended September 30,  | 
   | 
Nine Months Ended September 30,  | 
 
   | 
2018  | 
   | 
2017  | 
   | 
2018  | 
   | 
2017  | 
 
   | 
amounts in thousands  | 
 
Consolidated segment Adjusted OIBDA  | 
$  | 
50,740  | 
 
  | 
   | 
(5,277  | 
)  | 
   | 
136,352  | 
 
  | 
   | 
(20,071  | 
)  | 
 
Stock‑based compensation  | 
(7,761  | 
)  | 
   | 
(4,369  | 
)  | 
   | 
(20,926  | 
)  | 
   | 
(10,968  | 
)  | 
 
Depreciation and amortization  | 
(62,848  | 
)  | 
   | 
(823  | 
)  | 
   | 
(143,257  | 
)  | 
   | 
(2,398  | 
)  | 
 
Operating income (loss)  | 
(19,869  | 
)  | 
   | 
(10,469  | 
)  | 
   | 
(27,831  | 
)  | 
   | 
(33,437  | 
)  | 
 
Interest expense  | 
(37,614  | 
)  | 
   | 
—  | 
 
  | 
   | 
(81,304  | 
)  | 
   | 
—  | 
 
  | 
 
Share of earnings (loss) of affiliates, net  | 
10,856  | 
 
  | 
   | 
1,648  | 
 
  | 
   | 
18,714  | 
 
  | 
   | 
4,971  | 
 
  | 
 
Realized and unrealized gains (losses) on financial instruments, net  | 
495,509  | 
 
  | 
   | 
472,763  | 
 
  | 
   | 
(4,328  | 
)  | 
   | 
1,270,764  | 
 
  | 
 
Other, net  | 
(834  | 
)  | 
   | 
328  | 
 
  | 
   | 
(982  | 
)  | 
   | 
1,073  | 
 
  | 
 
Earnings (loss) from continuing operations before income taxes  | 
$  | 
448,048  | 
 
  | 
   | 
464,270  | 
 
  | 
   | 
(95,731  | 
)  | 
   | 
1,243,371  | 
 
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