AFFILIATE AND RELATED PARTY TRANSACTIONS - Amounts Due From and Due to Related Parties (Details) - USD ($) $ in Thousands, shares in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Shares purchased from a related party	14.9
Amount paid for shares repurchased from related party	$ 350,000
Affiliates
Related Party Transaction [Line Items]
Due from related parties and affiliates	4,554	$ 17,557
Due to related parties and affiliates	6,904	26,096
Affiliates | CVC 3
Related Party Transaction [Line Items]
Due from related parties and affiliates	0	13,100
Affiliates | Newsday
Related Party Transaction [Line Items]
Due from related parties and affiliates	475	490
Due to related parties and affiliates	0	22
Affiliates | Altice Europe
Related Party Transaction [Line Items]
Due from related parties and affiliates	67	1,271
Due to related parties and affiliates	0	15,235
Affiliates | Altice Dominican Republic
Related Party Transaction [Line Items]
Due from related parties and affiliates	3,435	2,550
Affiliates | Other Related Party
Related Party Transaction [Line Items]
Due from related parties and affiliates	577	146
Due to related parties and affiliates	4,486	5,975
Affiliates | Altice Labs S.A.
Related Party Transaction [Line Items]
Due to related parties and affiliates	$ 2,418	$ 4,864