INTANGIBLE ASSETS - Indefinite-lived assets (Details) - USD ($) $ in Thousands		1 Months Ended	9 Months Ended
	Apr. 06, 2021	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill			$ 8,206,365	$ 8,160,566
Cable television franchises			13,216,355	$ 13,068,017
Indefinite-lived Intangible Assets Acquired			148,338
Goodwill acquired			45,799
North Carolina Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Customer Relationships, Gross			58,777
Goodwill acquired			33,497
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			71,586
Consideration transfered	$ 312,184
Lightpath Acquired Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Customer Relationships, Gross			2,294
Goodwill acquired			12,302
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			$ 14,649
Consideration transfered		$ 28,260