AFFILIATE AND RELATED PARTY TRANSACTIONS - Amounts Due From and Due to Related Parties (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Payments to Acquire Other Investments					$ 2,500	$ 3,550
Affiliates
Related Party Transaction [Line Items]
Due from related parties and affiliates		$ 17,612					$ 19,764
Due to related parties and affiliates		24,392					10,998
Affiliates | Altice US Finance S.A.
Related Party Transaction [Line Items]
Due from related parties and affiliates		13,100					12,951
Affiliates | Newsday
Related Party Transaction [Line Items]
Due from related parties and affiliates		2,581					2,713
Due to related parties and affiliates		42					33
Affiliates | Altice Management Americas
Related Party Transaction [Line Items]
Due from related parties and affiliates		1,271					33
Affiliates | I24
Related Party Transaction [Line Items]
Due from related parties and affiliates		0					4,036
Affiliates | Altice Labs S.A.
Related Party Transaction [Line Items]
Due to related parties and affiliates		1,899					7,354
Affiliates | Other Altice N.V. subsidiaries
Related Party Transaction [Line Items]
Due from related parties and affiliates		660					31
Due to related parties and affiliates		9,201					3,611
Affiliates | Altice Management International
Related Party Transaction [Line Items]
Due to related parties and affiliates		13,250					$ 0
Equipment and Software Development Costs [Member] | Affiliates
Related Party Transaction [Line Items]
Payments to Acquire Other Investments		$ 1,108	$ 8,473		2,734	9,365
Other Operating Income (Expense) [Member] | Transition Services [Member] | Affiliates
Related Party Transaction [Line Items]
Related Party Transaction, Other Expenses from Transactions with Related Party	$ 505		$ 1,166		$ 999	964
Related Party Transaction, Other Revenues from Transactions with Related Party				$ 359		$ 841