Earnings (Loss) per Common Share (Diluted 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
Class A
Numerator:
Undistributed net income (loss) allocable to common stockholders for basic computation	$ (7,957)	$ 6,880	$ (66,197)	$ 10,834
Reallocation of undistributed earnings (loss) as a result of conversion of Class B to Class A shares	(774)	677	(6,545)	1,035
Reallocation of undistributed earnings as a result of conversion of dilutive securities	0	141	0	447
Effect of derivative instrument that may be settled in cash or shares	0	(2,827)	0	(9,327)
Effect of share based compensation that may be settled in cash or shares	0	(32)	0	(93)
Undistributed net income (loss) adjusted for allocation of undistributed earnings (loss) and effect of contracts that may be settled in cash or shares	$ (8,731)	$ 4,839	$ (72,742)	$ 2,896
Denominator:
Number of shares used in basic computation (shares)	31,374	32,033	31,291	33,008
Conversion of Class B to Class A common shares outstanding (shares)	3,052	3,154	3,094	3,154
Effect of derivative instrument that may be settled in cash or shares (shares)	0	264	0	602
Unexercised stock options (shares)	0	1	0	3
Effect of share based compensation that may be settled in cash or shares (shares)	0	26	0	26
Number of shares used in per share computation	34,426	35,478	34,385	36,793
Diluted net income (loss) attributable to GCI common stockholders per common share (USD per share)	$ (0.25)	$ 0.14	$ (2.12)	$ 0.08
Class B
Numerator:
Undistributed net income (loss) allocable to common stockholders for basic computation	$ (774)	$ 677	$ (6,545)	$ 1,035
Reallocation of undistributed earnings (loss) as a result of conversion of Class B to Class A shares	0	0	0	0
Reallocation of undistributed earnings as a result of conversion of dilutive securities	0	(247)	0	(787)
Effect of derivative instrument that may be settled in cash or shares	0	0	0	0
Effect of share based compensation that may be settled in cash or shares	0	0	0	0
Undistributed net income (loss) adjusted for allocation of undistributed earnings (loss) and effect of contracts that may be settled in cash or shares	$ (774)	$ 430	$ (6,545)	$ 248
Denominator:
Number of shares used in basic computation (shares)	3,052	3,154	3,094	3,154
Conversion of Class B to Class A common shares outstanding (shares)	0	0	0	0
Effect of derivative instrument that may be settled in cash or shares (shares)	0	0	0	0
Unexercised stock options (shares)	0	0	0	0
Effect of share based compensation that may be settled in cash or shares (shares)	0	0	0	0
Number of shares used in per share computation	3,052	3,154	3,094	3,154
Diluted net income (loss) attributable to GCI common stockholders per common share (USD per share)	$ (0.25)	$ 0.14	$ (2.12)	$ 0.08