v3.26.1
FAIR VALUE MEASUREMENT - Carrying Values and Estimated Fair Values of Debt Instruments (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
CSC Holdings | Related Party    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Notes payable to affiliate (Note 13) $ 78,500 $ 82,500
Fair Value, Inputs, Level 1 [Member] | Money market funds (a) | Fair Value Measured on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Money market funds (a) 825,563 937,365
Fair Value, Inputs, Level 1 [Member] | CSC Holdings | Money market funds (a) | Fair Value Measured on a Recurring Basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Money market funds (a) 817,662 929,604
Carrying Amount    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 26,438,596 26,100,595
Carrying Amount | Fair Value, Inputs, Level 2 [Member] | Unsub Group Credit Facility    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 2,923,712 1,898,893
Carrying Amount | Fair Value, Inputs, Level 2 [Member] | NYC ABS Receivable facility loan    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value   881,175
Carrying Amount | Fair Value, Inputs, Level 2 [Member] | CSC Holdings | Credit facility debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 5,033,627 5,613,602
Carrying Amount | Fair Value, Inputs, Level 2 [Member] | CSC Holdings | Senior guaranteed notes and senior secured notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 10,685,375 11,128,572
Carrying Amount | Fair Value, Inputs, Level 2 [Member] | CSC Holdings | Senior notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 6,162,803 6,578,353
Carrying Amount | Fair Value, Inputs, Level 2 [Member] | Cablevision Lightpath | Secured Fiber Network Revenue Notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 1,633,079  
Estimated Fair Value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 17,607,145 19,378,845
Estimated Fair Value | Fair Value, Inputs, Level 2 [Member] | Unsub Group Credit Facility    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 3,051,505 1,995,498
Estimated Fair Value | Fair Value, Inputs, Level 2 [Member] | CSC Holdings | Credit facility debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 4,937,500 5,621,683
Estimated Fair Value | Fair Value, Inputs, Level 2 [Member] | CSC Holdings | Senior guaranteed notes and senior secured notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 6,533,200 7,929,625
Estimated Fair Value | Fair Value, Inputs, Level 2 [Member] | CSC Holdings | Senior notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value 1,431,375 2,841,963
Estimated Fair Value | Fair Value, Inputs, Level 2 [Member] | Cablevision Lightpath | Secured Fiber Network Revenue Notes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value $ 1,653,565  
Estimated Fair Value | Fair Value, Inputs, Level 3 | NYC ABS Receivable facility loan    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt, fair value   $ 990,076