Liberty Broadband Corporation Quarterly report pursuant to Section 13 or 15(d)

Information About the Company's Operating Segments (Other Information) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 9,880,457	$ 6,172,213
Investments accounted for using the equity method	174,134	$ 114,655
Capital expenditures	89,376
Operating Segments
Segment Reporting Information [Line Items]
Total assets	21,963,131
Investments accounted for using the equity method	12,151,502
Capital expenditures	89,411
Operating Segments \| GCI Holdings
Segment Reporting Information [Line Items]
Total assets	3,561,569
Investments accounted for using the equity method	0
Capital expenditures	86,977
Operating Segments \| Liberty Broadband
Segment Reporting Information [Line Items]
Total assets	12,082,674
Investments accounted for using the equity method	11,977,368
Capital expenditures	35
Operating Segments \| Corporate and other
Segment Reporting Information [Line Items]
Total assets	6,318,888
Investments accounted for using the equity method	174,134
Capital expenditures	2,399
Consolidation, Eliminations
Segment Reporting Information [Line Items]
Total assets	(12,082,674)
Investments accounted for using the equity method	(11,977,368)
Capital expenditures	$ (35)