Segment Reporting and Significant Concentration - Summary of Net Billed Accounts Receivable from Significant Customers (Details) - Accounts Receivable - Customer Concentration Risk	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Comcast
Trade accounts receivable:
Accounts Receivable by Significant Client, Percentage	19.00%	24.00%
Charter
Trade accounts receivable:
Accounts Receivable by Significant Client, Percentage	20.00%	24.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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