Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Total	$ 210,146	$ 5,493	$ 504,840	$ 15,639
Lease, grant, and revenue from subsidies
Disaggregation of Revenue [Line Items]
Total	24,226		55,114
GCI Holdings | Consumer Revenue | Wireless
Disaggregation of Revenue [Line Items]
Revenues	25,584		62,312
GCI Holdings | Consumer Revenue | Data
Disaggregation of Revenue [Line Items]
Revenues	39,652		88,921
GCI Holdings | Consumer Revenue | Video
Disaggregation of Revenue [Line Items]
Revenues	22,272		50,180
GCI Holdings | Consumer Revenue | Voice
Disaggregation of Revenue [Line Items]
Revenues	4,368		10,246
GCI Holdings | Business Revenue | Wireless
Disaggregation of Revenue [Line Items]
Revenues	18,071		44,889
GCI Holdings | Business Revenue | Data
Disaggregation of Revenue [Line Items]
Revenues	59,585		154,239
GCI Holdings | Business Revenue | Video
Disaggregation of Revenue [Line Items]
Revenues	4,927		9,436
GCI Holdings | Business Revenue | Voice
Disaggregation of Revenue [Line Items]
Revenues	6,361		14,282
Evite
Disaggregation of Revenue [Line Items]
Revenues	$ 5,100		$ 15,221