Earnings (Loss) per Common Share (Basic Net Income (Loss) per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net income (loss) available to common stockholders	$ (8,731)	$ 7,943	$ (72,742)	$ 12,457
Class A
Numerator:
Net income (loss) available to common stockholders	(7,957)	7,266	(66,197)	11,422
Less: Undistributed net income allocable to participating securities	0	(386)	0	(588)
Undistributed net income (loss) allocable to common stockholders	$ (7,957)	$ 6,880	$ (66,197)	$ 10,834
Denominator:
Weighted average common shares outstanding	31,374	32,033	31,291	33,008
Basic net income (loss) attributable to GCI common stockholders per common share (USD per share)	$ (0.25)	$ 0.21	$ (2.12)	$ 0.33
Class B
Numerator:
Net income (loss) available to common stockholders	$ (774)	$ 677	$ (6,545)	$ 1,035
Less: Undistributed net income allocable to participating securities	0	0	0	0
Undistributed net income (loss) allocable to common stockholders	$ (774)	$ 677	$ (6,545)	$ 1,035
Denominator:
Weighted average common shares outstanding	3,052	3,154	3,094	3,154
Basic net income (loss) attributable to GCI common stockholders per common share (USD per share)	$ (0.25)	$ 0.21	$ (2.12)	$ 0.33