SEGMENT INFORMATION - Reconciliation of Adjusted EBITDA to Operating Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Income (Loss) from Continuing Operations Before Income Taxes [Abstract]
Operating income	$ 313,038	$ 250,110
Share-based compensation expense	21,623	7,848
Restructuring and other expense	3,587	76,929
Depreciation and amortization (including impairments)	642,705	608,724
Adjusted EBITDA	980,953	943,611
Cablevision
Operating Income (Loss) from Continuing Operations Before Income Taxes [Abstract]
Operating income	170,693	122,044
Share-based compensation expense	16,172	5,082
Restructuring and other expense	3,083	58,647
Depreciation and amortization (including impairments)	485,364	443,176
Adjusted EBITDA	675,312	628,949
Cequel
Operating Income (Loss) from Continuing Operations Before Income Taxes [Abstract]
Operating income	142,345	128,066
Share-based compensation expense	5,451	2,766
Restructuring and other expense	504	18,282
Depreciation and amortization (including impairments)	157,341	165,548
Adjusted EBITDA	$ 305,641	$ 314,662