INCOME TAXES - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Federal tax expense (benefit) at statutory rate	$ 39,297	$ (3,793)	$ (478,656)
State income taxes, net of federal impact	(6,256)	(8,103)	(61,698)
Changes in the valuation allowance	4,079	15,987	(111)
Impact of Federal Tax Reform	0	0	(2,332,677)
Changes in the state rates used to measure deferred taxes, net of federal impact	(1,046)	(52,915)	(12,896)
Tax benefit relating to uncertain tax positions	(847)	(514)	(253)
Non-deductible share-based compensation related to the carried unit plan	15,642	8,677	20,101
Other non-deductible expenses	1,334	2,200	3,405
Other, net	(5,013)	(194)	433
Income tax expense (benefit)	$ 47,190	(38,655)	(2,862,352)
Percentage request for prior year AMT	75.00%
CSC Holdings
Federal tax expense (benefit) at statutory rate	$ 59,653	66,757	(83,507)
State income taxes, net of federal impact	(9,060)	33,249	(23,720)
Changes in the valuation allowance	4,307	0	0
Impact of Federal Tax Reform	0	0	(2,731,324)
Changes in the state rates used to measure deferred taxes, net of federal impact	6,532	(53,493)	(12,999)
Tax benefit relating to uncertain tax positions	(847)	(514)	(253)
Non-deductible share-based compensation related to the carried unit plan	15,642	8,677	20,101
Other non-deductible expenses	1,334	2,011	3,383
Other, net	(6,318)	876	568
Income tax expense (benefit)	$ 71,243	$ 57,563	$ (2,827,751)