DEBT - Schedule of Gain (Loss) on Debt Extinguishment (Details) - USD ($) $ in Thousands		12 Months Ended
	Mar. 15, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs	$ 18,976	$ 243,806	$ 48,804	$ 600,240
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)	$ (18,976)	(243,806)	(48,804)	(600,240)
CSC Holdings
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs		228,130	7,883	53,988
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)		(228,130)	(7,883)	(53,988)
Altice USA
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs				513,723
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)				(513,723)
7.75% Notes due April 15, 2018
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs			4,706
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)			(4,706)
Cequel Credit Facilities
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs			7,733	2,455
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)			(7,733)	(2,455)
CSC Holdings Term Loan B
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs				12,675
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)				(12,675)
10.875% Notes due October 15, 2025
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs				38,858
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)				(38,858)
Cequel 6.375% Senior Notes due 2020
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs			36,910	26,229
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)			(36,910)	(26,229)
8.0% Notes due April 15, 2020
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs		15,176
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)		(15,176)
Cablevision 5.125% Notes due December 15, 2021
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs		500
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)		(500)
CSC Holdings 5.125% Notes due December 15, 2021
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs		65,151
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)		(65,151)
10.125% Notes due January 15, 2023
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs		154,666
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)		(154,666)
CSC Holdings Term Loan Facility
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs		8,313
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)		$ (8,313)
Cequel Notes relating to Debt Exchange
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs			(695)
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)			695
Cequel Notes relating to Debt Exchange | CSC Holdings
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs			150
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)			$ (150)
8.625% Notes due September 15, 2017
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs				6,300
Loss on extinguishment of debt and write-off of deferred financing costs (including $513,723 related to affiliates and related parties in 2017) (See Note 16)				$ (6,300)