SEGMENT INFORMATION - Summary of Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue from External Customer [Line Items]
Revenues	$ 2,364,153	$ 2,322,362	$ 4,693,867	$ 4,624,621
Pay TV
Revenue from External Customer [Line Items]
Revenues	1,034,404	1,071,163	2,068,112	2,155,041
Broadband
Revenue from External Customer [Line Items]
Revenues	712,202	642,620	1,413,823	1,268,538
Telephony
Revenue from External Customer [Line Items]
Revenues	163,499	178,261	329,537	359,222
Business services and wholesale
Revenue from External Customer [Line Items]
Revenues	337,388	323,641	670,478	643,061
Advertising
Revenue from External Customer [Line Items]
Revenues	109,898	97,501	197,480	180,862
Other
Revenue from External Customer [Line Items]
Revenues	6,762	9,176	14,437	17,897
Operating Segments | Cablevision
Revenue from External Customer [Line Items]
Revenues	1,685,727	1,659,526	3,337,021	3,301,513
Operating Segments | Cablevision | Pay TV
Revenue from External Customer [Line Items]
Revenues	766,257	796,456	1,529,977	1,598,650
Operating Segments | Cablevision | Broadband
Revenue from External Customer [Line Items]
Revenues	449,426	405,199	889,777	801,532
Operating Segments | Cablevision | Telephony
Revenue from External Customer [Line Items]
Revenues	133,635	145,323	269,220	291,880
Operating Segments | Cablevision | Business services and wholesale
Revenue from External Customer [Line Items]
Revenues	236,763	230,964	470,935	459,508
Operating Segments | Cablevision | Advertising
Revenue from External Customer [Line Items]
Revenues	95,981	78,802	170,624	143,934
Operating Segments | Cablevision | Other
Revenue from External Customer [Line Items]
Revenues	3,665	2,782	6,488	6,009
Operating Segments | Cequel Corp. [Member]
Revenue from External Customer [Line Items]
Revenues	682,875	662,836	1,365,424	1,323,108
Operating Segments | Cequel Corp. [Member] | Pay TV
Revenue from External Customer [Line Items]
Revenues	268,147	274,707	538,135	556,391
Operating Segments | Cequel Corp. [Member] | Broadband
Revenue from External Customer [Line Items]
Revenues	262,776	237,421	524,046	467,006
Operating Segments | Cequel Corp. [Member] | Telephony
Revenue from External Customer [Line Items]
Revenues	29,864	32,938	60,317	67,342
Operating Segments | Cequel Corp. [Member] | Business services and wholesale
Revenue from External Customer [Line Items]
Revenues	100,625	92,677	199,543	183,553
Operating Segments | Cequel Corp. [Member] | Advertising
Revenue from External Customer [Line Items]
Revenues	18,366	18,699	35,434	36,928
Operating Segments | Cequel Corp. [Member] | Other
Revenue from External Customer [Line Items]
Revenues	3,097	$ 6,394	7,949	$ 11,888
Eliminations
Revenue from External Customer [Line Items]
Revenues	(4,449)		(8,578)
Eliminations | Pay TV
Revenue from External Customer [Line Items]
Revenues	0		0
Eliminations | Broadband
Revenue from External Customer [Line Items]
Revenues	0		0
Eliminations | Telephony
Revenue from External Customer [Line Items]
Revenues	0		0
Eliminations | Business services and wholesale
Revenue from External Customer [Line Items]
Revenues	0		0
Eliminations | Advertising
Revenue from External Customer [Line Items]
Revenues	(4,449)		(8,578)
Eliminations | Other
Revenue from External Customer [Line Items]
Revenues	$ 0		$ 0