|**Stockholders' Equity**       | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
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|**Equity [Abstract]**          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Stockholders' Equity           | Stockholders’ EquityCommon StockGCI’s Class A-1 and Class B-1 common stock are identical in all respects, except that each share of Class A-1 common stock hasonevote per share and each share of Class B-1 common stock hastenvotes per share. Each share of Class B-1 common stock outstanding is convertible, at the option of the holder, intooneshare of Class A-1 common stock.GCI’s Board of Directors has authorized a common stock buyback program for the repurchase of GCI’s Class A-1 and Class B-1 common stock in order to reduce the outstanding shares of Class A-1 and Class B-1 common stock.  We have temporarily suspended the buyback program due to the Reorganization Agreement that we entered into with Liberty (see Note15)During the years endedDecember 31, 2017,2016and2015we repurchased0.2 million,3.5 million, and3.0 millionshares, respectively, of our Class A-1 common stock under the stock buyback program at a cost of$4.0 million,$55.2 millionand$47.4 million, respectively.  Under this program we are currently authorized to make up to$61.2 millionof repurchases as ofDecember 31, 2017.Shared-Based CompensationOur Amended and Restated 1986 Stock Option Plan ("Stock Option Plan"), provides for the grant of restricted stock awards for a maximum of15.7 millionshares of GCIClass A-1 common stock, subject to adjustment upon the occurrence of stock dividends, stock splits, mergers, consolidations or certain other changes in corporate structure or capitalization. If an awardexpires or terminates, the shares subject to the award will be available for further grants of awards under the Stock Option Plan. The Compensation Committee of GCI’s Board of Directors administers theStock Option Plan. Substantially all restricted stock awards granted vest over periods of up tothreeyears. The requisite service period of our awards is generally the same as the vesting period.  New shares are issued when restricted stock awards are granted. We have1.2 millionshares available for grant under the Stock Option Plan atDecember 31, 2017.A summary of nonvested restricted stock award activity under the Stock Option Plan for the year endedDecember 31, 2017, follows (share amounts in thousands):SharesWeightedAverageGrant DateFair ValueNonvested at January 1, 20161,465$14.41Granted607$23.24Vested(894)$16.22Forfeited(5)$18.48Nonvested at December 31, 20161,173$17.58The weighted average grant date fair value of awards granted during the years endedDecember 31, 2017,2016, and2015were$23.24,$17.87and$15.06, respectively.  The total fair value of awards vesting during the years endedDecember 31, 2017,2016, and2015were$29.9 million,$13.5 millionand$17.0 million, respectively. We have recorded share-based compensation expense of$17.5 million,$11.0 million, and$10.9 millionfor the years endedDecember 31, 2017,2016, and2015, respectively.  Share-based compensation expense is classified as Selling, General and Administrative Expense in our Consolidated Statements of Operations.  Unrecognized share-based compensation expense is$11.3 millionas ofDecember 31, 2017.  We expect to recognize share-based compensation expense over a weighted average period of1.6years for restricted stock awards.GCI 401(k) PlanIn 1986, we adopted an Employee Stock Purchase Plan (“GCI 401(k) Plan”) qualified under Section 401 of the Internal Revenue Code of 1986. The GCI 401(k) Plan provides for acquisition of GCI’s Class A-1common stock at market value as well as various mutual funds. We may match a percentage of the employees' contributions up to certain limits, decided by GCI’s Board of Directors each year. Our matching contributions allocated to participant accounts totaled$11.0 million,$11.0 millionand$9.8 millionfor the years endedDecember 31, 2017,2016and2015, respectively.  We used cash to fund all of our employer-matching contributions during the years endedDecember 31, 2017,2016and2015.
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|                               | Shares                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|Nonvested at January 1, 2016   | 1,465                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|Granted                        | 607                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
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|Forfeited                      | (5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Nonvested at December 31, 2016 | 1,173                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

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