DEBT - Schedule of Gain (Loss) on Debt Extinguishment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs	$ 503	$ 0	$ 159,599	$ 41,616
Cablevision Systems Corp. | Senior Notes | Cablevision 5.125% Notes due December 15, 2021
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs	(503)		(503)
CSC Holdings | Senior Notes | Cablevision 7.75% Notes due April 15, 2018 [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs		0		4,706
CSC Holdings | Senior Notes | 7.75% Notes due April 15, 2018
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs	0		154,666
Revolving Credit Facility | CSC Holdings
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs	$ 0		$ 4,430	$ 36,910
5.375% Senior Guaranteed Notes Due February 1, 2028 [Member] | CSC Holdings
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs		$ 0