INTANGIBLE ASSETS - Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Goodwill [Line Items]
Goodwill, Acquired During Period	$ 7,608
Goodwill [Roll Forward]
Goodwill, beginning balance	8,019,861
Adjustments to purchase accounting relating to Cablevision Acquisition	(12)
Goodwill, ending balance	8,012,416
As Reported
Goodwill [Roll Forward]
Goodwill, beginning balance	7,996,760
ATS Acquisition | Restatement Adjustment
Goodwill [Roll Forward]
Goodwill, beginning balance	23,101
Suddenlink [Member]
Goodwill [Roll Forward]
Adjustments to purchase accounting relating to Cablevision Acquisition	$ (15,041)