Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (GCI 401(k) Plan) (Details)

v3.8.0.1
Stockholders' Equity (GCI 401(k) Plan) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Equity [Abstract]      
Matching contributions $ 11.0 $ 11.0 $ 9.8