Information About the Company's Operating Segments - (Adjusted OIBDA) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Adjusted OIBDA	$ 75,699	$ 66,806	$ 220,775	$ 167,552
Operating Segments
Segment Reporting Information [Line Items]
Adjusted OIBDA	61,429	62,220	194,117	155,675
Operating Segments | GCI Holdings
Segment Reporting Information [Line Items]
Adjusted OIBDA	91,617	71,960	256,057	182,552
Operating Segments | Liberty Broadband
Segment Reporting Information [Line Items]
Adjusted OIBDA	(14,270)	(4,586)	(26,658)	(11,877)
Operating Segments | Corporate and other
Segment Reporting Information [Line Items]
Adjusted OIBDA	(15,918)	(5,154)	(35,282)	(15,000)
Consolidation, Eliminations
Segment Reporting Information [Line Items]
Adjusted OIBDA	$ 14,270	$ 4,586	$ 26,658	$ 11,877