Goodwill and Intangible Assets (Rollforward) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Balance at beginning of period	$ 844,182	$ 25,569
Acquisitions		966,044
Impairment	0	(147,431)
Balance at end of period	844,182	844,182
GCI Holdings
Goodwill [Roll Forward]
Balance at beginning of period	818,613	0
Acquisitions		966,044
Impairment	0	(147,431)
Balance at end of period	818,613	818,613
Corporate and other
Goodwill [Roll Forward]
Balance at beginning of period	25,569	25,569
Acquisitions		0
Impairment	0	0
Balance at end of period	$ 25,569	$ 25,569