DEBT - Schedule of Gain (Loss) on Debt Extinguishment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs	$ 0	$ 250,489	$ 51,712	$ 250,489
Loss on extinguishment of debt and write-off of deferred financing costs	0	(250,489)	(51,712)	(250,489)
CSC Holdings
Debt Instrument [Line Items]
Loss on extinguishment of debt and write-off of deferred financing costs	0	250,489	51,712	250,489
Loss on extinguishment of debt and write-off of deferred financing costs	$ 0	$ (250,489)	$ (51,712)	$ (250,489)