Related Party Transactions (Narrative) (Details) - Board of Directors Chairman	Sep. 30, 2020
Liberty Global
Related Party Transaction [Line Items]
Aggregate voting power percentage of a related party	30.00%
Liberty Broadband
Related Party Transaction [Line Items]
Aggregate voting power percentage of a related party	48.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration