AFFILIATE AND RELATED PARTY TRANSACTIONS - Amounts Due From and Due to Related Parties (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Jun. 30, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Treasury Stock, Shares, Acquired	20,209		20,887
Payments for Repurchase of Common Stock	$ 0	$ 503,645
Share based compensation expense	40,532	28,281
Related party expense	7,075	2,001
Stock options | 2017 LTIP
Related Party Transaction [Line Items]
Share based compensation expense	22,497	24,223
Restricted Stock | 2019 LTIP
Related Party Transaction [Line Items]
Share based compensation expense	16,009	317
CSC Holdings
Related Party Transaction [Line Items]
Cash distributions to parent	0	(501,000)
Cash distributions	0	501,000
Non-cash distributions to parent		(748)
CSC Holdings | Member's Deficiency
Related Party Transaction [Line Items]
Cash distributions to parent		(501,000)
Non-cash distributions to parent	0	$ (748)
Affiliates
Related Party Transaction [Line Items]
Due from related parties and affiliates	3,830			$ 3,776
Due to related parties and affiliates	22,872			31,810
Affiliates | Altice Management Americas
Related Party Transaction [Line Items]
Due from related parties and affiliates	295			241
Affiliates | Other Related Party
Related Party Transaction [Line Items]
Due from related parties and affiliates	3,535			3,535
Due to related parties and affiliates	1,348			1,206
Affiliates | Altice Management International
Related Party Transaction [Line Items]
Due to related parties and affiliates	$ 21,524			$ 30,604