Goodwill and Intangible Assets (Rollforward) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 25,569
Acquisitions	966,044
Impairment	(147,431)
Balance at end of period	844,182
GCI Holdings
Goodwill [Roll Forward]
Balance at beginning of period	0
Acquisitions	966,044
Balance at end of period	818,613
Corporate and other
Goodwill [Roll Forward]
Balance at beginning of period	25,569
Acquisitions	0
Impairment	0
Balance at end of period	$ 25,569