CSC HOLDINGS - CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 1,952,142				$ 1,952,142		$ 701,898
Restricted cash	264				264		262
Accounts receivable, trade (less allowance for doubtful accounts of $13,420 and $11,677)	387,739				387,739		457,118
Prepaid expenses and other current assets (including a prepayment to an affiliate of $19,563 in 2017) (See Note 14)	209,916				209,916		215,304
Amounts due from affiliates	3,452				3,452		6,774
Operating Lease, Right-of-Use Asset	270,592				270,592		280,340
Total current assets	2,553,513				2,553,513		1,381,356
Property, plant and equipment, net	5,723,109				5,723,109		5,753,401
Investment securities pledged as collateral	1,674,395				1,674,395		1,931,697
Derivative contracts	225,791				225,791		25,207
Other assets	106,840				106,840		92,622
Amortizable intangible assets, net of accumulated amortization	3,097,216				3,097,216		3,481,109
Indefinite-lived cable television franchises	13,020,081				13,020,081		13,020,081
Goodwill	8,142,309				8,142,309		8,142,309
Total assets	34,813,846				34,813,846		34,108,122
Current Liabilities:
Accounts payable	832,011				832,011		799,618
Amounts due to affiliates	5,722				5,722		7,456
Accrued liabilities:
Interest payable	381,482				381,482		385,655
Accrued employee related costs	109,334				109,334		111,337
Other Accrued Liabilities, Current	387,212				387,212		378,954
Contract with Customer, Liability, Current	117,925				117,925		124,777
Long-term Debt, Current Maturities	1,859,290				1,859,290		170,682
Total current liabilities	3,692,976				3,692,976		1,978,479
Other liabilities	215,781				215,781		204,904
Deferred tax liability	4,833,305				4,833,305		4,762,595
Liabilities under derivative contracts	312,916				312,916		255,666
Long-term Debt, Right-Of-Use Financing Obligations, Excluding Current Maturities	259,297				259,297		269,062
Long-term Debt, Excluding Current Maturities	24,326,397				24,326,397		24,249,603
Total liabilities	33,640,672				33,640,672		31,720,309
Commitments and contingencies
Redeemable equity	15,495				15,495		108,551
Limited Liability Company (LLC) Members' Equity [Abstract]
Retained earnings (accumulated deficit)	501,172				501,172		390,766
Accumulated other comprehensive income (loss)	(12,118)				(12,118)		(3,250)
Noncontrolling interest	8,831				8,831		9,298
Total liabilities and equity	34,813,846				34,813,846		34,108,122
Net Income (Loss) Attributable to Noncontrolling Interest	213	$ (680)	$ 43	$ (199)	(467)	$ (156)
Customer Relationships [Member]
Current Assets:
Amortizable intangible assets, net of accumulated amortization	2,843,070				2,843,070		3,173,963
Other Intangible Assets [Member]
Current Assets:
Amortizable intangible assets, net of accumulated amortization	19,992				19,992		24,547
CSC Holdings
Current Assets:
Cash and cash equivalents	1,952,128				1,952,128		697,741
Restricted cash	264				264		262
Accounts receivable, trade (less allowance for doubtful accounts of $13,420 and $11,677)	387,739				387,739		457,118
Prepaid expenses and other current assets (including a prepayment to an affiliate of $19,563 in 2017) (See Note 14)	209,916				209,916		211,642
Amounts due from affiliates	3,322				3,322		6,774
Operating Lease, Right-of-Use Asset	270,592				270,592		280,340
Total current assets	2,553,369				2,553,369		1,373,537
Property, plant and equipment, net	5,723,109				5,723,109		5,753,401
Investment securities pledged as collateral	1,674,395				1,674,395		1,931,697
Derivative contracts	225,791				225,791		25,207
Other assets	106,840				106,840		92,622
Amortizable intangible assets, net of accumulated amortization	3,097,216				3,097,216		3,481,109
Indefinite-lived cable television franchises	13,020,081				13,020,081		13,020,081
Goodwill	8,142,309				8,142,309		8,142,309
Total assets	34,813,702				34,813,702		34,100,303
Current Liabilities:
Accounts payable	832,011				832,011		799,618
Amounts due to affiliates	5,722				5,722		7,456
Accrued liabilities:
Interest payable	381,482				381,482		385,655
Accrued employee related costs	109,334				109,334		111,337
Other Accrued Liabilities, Current	387,212				387,212		378,948
Contract with Customer, Liability, Current	117,925				117,925		124,777
Long-term Debt, Current Maturities	1,859,290				1,859,290		170,682
Total current liabilities	3,692,976				3,692,976		1,978,473
Other liabilities	215,779				215,779		204,904
Deferred tax liability	5,156,281				5,156,281		4,980,599
Liabilities under derivative contracts	312,916				312,916		255,666
Long-term Debt, Right-Of-Use Financing Obligations, Excluding Current Maturities	259,297				259,297		269,062
Long-term Debt, Excluding Current Maturities	24,326,397				24,326,397		24,249,603
Total liabilities	33,963,646				33,963,646		31,938,307
Redeemable equity	15,495				15,495		108,551
Limited Liability Company (LLC) Members' Equity [Abstract]
Members' Equity	830,368				830,368		2,033,882
Retained earnings (accumulated deficit)	7,480				7,480		13,515
Membership interest before accumulated comprehensive loss	837,848				837,848		2,047,397
Accumulated other comprehensive income (loss)	(12,118)				(12,118)		(3,250)
Membership equity before noncontrolling interest	825,730				825,730		2,044,147
Noncontrolling interest	8,831	8,618			8,831		9,298
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest	834,561	1,252,797	2,857,921	3,352,567	834,561	2,857,921	2,053,445	$ 3,999,140
Total liabilities and equity	34,813,702				34,813,702		$ 34,100,303
Net Income (Loss) Attributable to Noncontrolling Interest	$ 213	$ (680)	$ 43	$ (199)	$ (467)	$ (156)